[SDK-115] Drop branches: filter on pull_request so stacked PRs trigger BCIT

The `branches:` key under `pull_request:` filters by the PR's *target*
branch, not its head — so PRs targeting long-lived integration branches
(e.g. the followup #1062 targeting SDK-115-bcit-ci) silently skipped this
workflow. Path filters still gate which PRs actually fire it; only PRs
that touch integration-tests / iterableapi(-ui) / the workflow / the
run-e2e.sh script will trigger.

Push trigger keeps `branches: [master]` so we don't double-run on every
feature branch's push events alongside its PR run.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: franco-zalamena-iterable

.github/workflows/integration-tests-bcit.yml

@@ -12,7 +12,10 @@ on:
       - '.github/workflows/integration-tests-bcit.yml'
       - '.github/scripts/run-e2e.sh'
   pull_request:
-    branches: [ master ]
+    # No `branches:` filter — `branches:` matches the PR's *target*, not its head, so
+    # restricting to [master] silently skips stacked PRs that target SDK-115-* (or any
+    # other long-lived integration branch). Path filters below still gate which PRs
+    # actually trigger the workflow.
     paths:
       - 'integration-tests/**'
       - 'iterableapi/**'