[Security Solution][Endpoint] Change where agent diagnostic files saved on test failures for cypress suites (elastic#220272)

## Summary

- Changes the location of any captured Elastic agent diagnostics files
during a cypress tests failure to `target/agent_diagnostics` from
`target/test_failures`

Author: paul-tavares

.buildkite/scripts/lifecycle/post_command.sh

@@ -54,6 +54,10 @@ if [[ "$IS_TEST_EXECUTION_STEP" == "true" ]]; then
     ts-node .buildkite/scripts/lifecycle/annotate_test_failures.ts
   fi
 
+  if [[ -d 'target/agent_diagnostics' ]]; then
+    buildkite-agent artifact upload 'target/agent_diagnostics/**/*'
+  fi
+
 fi
 
 if [[ $BUILDKITE_COMMAND_EXIT_STATUS -ne 0 ]]; then

x-pack/solutions/security/plugins/security_solution/public/management/cypress/support/data_loaders.ts

@@ -577,7 +577,7 @@ ${s1Info.status}
         .toISOString()
         .replace(/:/g, '.')}.zip`;
       const vmDiagnosticsFile = `/tmp/${fileName}`;
-      const localDiagnosticsDir = `${REPO_ROOT}/target/test_failures`;
+      const localDiagnosticsDir = `${REPO_ROOT}/target/agent_diagnostics`;
       const localDiagnosticsFile = `${localDiagnosticsDir}/${
         fileNamePrefix
           ? // Insure the file name prefix does not have characters that can't be used in file names