[9.2] Fix APM trace.id emission test (#244875) (#245435)

# Backport

This will backport the following commits from `main` to `9.2`:
- [Fix APM `trace.id` emission test
(#244875)](#244875)

<!--- Backport version: 9.6.6 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

<!--BACKPORT [{"author":{"name":"Jean-Louis
Leysens","email":"jeanlouis.leysens@elastic.co"},"sourceCommit":{"committedDate":"2025-12-05T18:25:30Z","message":"Fix
APM `trace.id` emission test (#244875)\n\n## Summary\n\nClose
https://github.com/elastic/kibana/issues/244713\n\nUpdate `Log
Correlation Emits \"trace.id\" into the logs` to no longer\ncheck for
unique `trace.id` values in subsequent requests as this is not\nthe
primary focus of this test.\n\n### More details\n\nAfter merging [APM
for
functional\ntest](https://github.com/elastic/kibana/pull/228692/files#diff-deac86b8f74f0b46cc5bb277f8d20a5a3de5ffd6c14bdf9de555734bc58fce57R11)\nruns
the `Log Correlation Emits \"trace.id\" into the logs` test
started\nfailing because it was no longer possible to test that unique
`trace.id`\nvalues were being generated for subsequent
requests:\n\n```\n └- ✖ fail: Execution context Log Correlation Emits
\"trace.id\" into the logs\n │ Error: expected
'53f48249e3207b30ed63f76b4d4913ea' to not equal
'53f48249e3207b30ed63f76b4d4913ea'\n```","sha":"00d38597d6ed66e56b25d29523f824a8fb901847","branchLabelMapping":{"^v9.3.0$":"main","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["Team:Core","release_note:skip","backport:all-open","v9.3.0"],"title":"Fix
APM `trace.id` emission
test","number":244875,"url":"https://github.com/elastic/kibana/pull/244875","mergeCommit":{"message":"Fix
APM `trace.id` emission test (#244875)\n\n## Summary\n\nClose
https://github.com/elastic/kibana/issues/244713\n\nUpdate `Log
Correlation Emits \"trace.id\" into the logs` to no longer\ncheck for
unique `trace.id` values in subsequent requests as this is not\nthe
primary focus of this test.\n\n### More details\n\nAfter merging [APM
for
functional\ntest](https://github.com/elastic/kibana/pull/228692/files#diff-deac86b8f74f0b46cc5bb277f8d20a5a3de5ffd6c14bdf9de555734bc58fce57R11)\nruns
the `Log Correlation Emits \"trace.id\" into the logs` test
started\nfailing because it was no longer possible to test that unique
`trace.id`\nvalues were being generated for subsequent
requests:\n\n```\n └- ✖ fail: Execution context Log Correlation Emits
\"trace.id\" into the logs\n │ Error: expected
'53f48249e3207b30ed63f76b4d4913ea' to not equal
'53f48249e3207b30ed63f76b4d4913ea'\n```","sha":"00d38597d6ed66e56b25d29523f824a8fb901847"}},"sourceBranch":"main","suggestedTargetBranches":[],"targetPullRequestStates":[{"branch":"main","label":"v9.3.0","branchLabelMappingKey":"^v9.3.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/244875","number":244875,"mergeCommit":{"message":"Fix
APM `trace.id` emission test (#244875)\n\n## Summary\n\nClose
https://github.com/elastic/kibana/issues/244713\n\nUpdate `Log
Correlation Emits \"trace.id\" into the logs` to no longer\ncheck for
unique `trace.id` values in subsequent requests as this is not\nthe
primary focus of this test.\n\n### More details\n\nAfter merging [APM
for
functional\ntest](https://github.com/elastic/kibana/pull/228692/files#diff-deac86b8f74f0b46cc5bb277f8d20a5a3de5ffd6c14bdf9de555734bc58fce57R11)\nruns
the `Log Correlation Emits \"trace.id\" into the logs` test
started\nfailing because it was no longer possible to test that unique
`trace.id`\nvalues were being generated for subsequent
requests:\n\n```\n └- ✖ fail: Execution context Log Correlation Emits
\"trace.id\" into the logs\n │ Error: expected
'53f48249e3207b30ed63f76b4d4913ea' to not equal
'53f48249e3207b30ed63f76b4d4913ea'\n```","sha":"00d38597d6ed66e56b25d29523f824a8fb901847"}}]}]
BACKPORT-->

Co-authored-by: Jean-Louis Leysens <jeanlouis.leysens@elastic.co>

Author: kibanamachine

x-pack/platform/test/functional_execution_context/tests/log_correlation.ts

@@ -29,24 +29,23 @@ export default function ({ getService }: FtrProviderContext) {
   const log = getService('log');
 
   describe('Log Correlation', () => {
-    // TODO: see https://github.com/elastic/kibana/pull/243499
-    it.skip('Emits "trace.id" into the logs', async () => {
+    it('Emits "trace.id" into the logs', async () => {
       if (isPrWithLabel('"ci:collect-apm"')) {
         log.warning(`Skipping test as APM is enabled in FTR, which breaks this test`);
         return;
       }
 
-      const response1 = await supertest.get('/emit_log_with_trace_id');
-      expect(response1.status).to.be(200);
-
+      // Explicitly unset traceparent so that APM agent provides a new trace.id for the request
+      const response1 = await supertest.get('/emit_log_with_trace_id').set('traceparent', '');
       expect(response1.body.traceId).to.be.a('string');
+      expect(response1.status).to.be(200);
 
-      const response2 = await supertest.get('/emit_log_with_trace_id');
-
+      // Explicitly unset traceparent so that APM agent provides a new trace.id for the request
+      const response2 = await supertest.get('/emit_log_with_trace_id').set('traceparent', '');
+      expect(response2.body.traceId).to.be.a('string');
       expect(response2.status).to.be(200);
-      expect(response1.body.traceId).to.be.a('string');
 
-      expect(response2.body.traceId).not.to.be(response1.body.traceId);
+      expect(response1.body.traceId).not.to.be(response2.body.traceId);
 
       const logs = await readLogFile();
 
@@ -79,7 +78,6 @@ export default function ({ getService }: FtrProviderContext) {
               // esClient.ping() request
               record.message?.includes('HEAD /')
           ),
-
         logs,
       });
     });