Allow e2e untrusted outcome to skip if PR is from same repo (#761)

*Issue #, if available:*

*Description of changes:*

Small fix for PR #702 where the outcome job (All E2E Tests Passed) fails
for PRs from the same repo and not from forks (e.g. dependabot PRs).
Non-blocking since "E2E Tests (Untrusted) / All E2E Tests Passed
(pull_request_target)" is not required in same repo PRs (see #748).

*Testing:* (See PR)

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---------

Signed-off-by: Jensen Tong <jetong@amazon.com>

Author: jet-tong

.github/workflows/e2e-test-untrusted.yaml

@@ -39,7 +39,7 @@ jobs:
     secrets: inherit
   outcome:
     name: All E2E Tests Passed
-    if: always()
+    if: ${{ always() && github.event.pull_request.head.repo.id != github.event.pull_request.base.repo.id }}
     runs-on: ubuntu-latest
     needs:
       - e2e