Bug fix for trigger pipeline Buildkite pipeline (#15700)

This commit fixes a few bugs introduced in #15668 related to paths for
the calling script. We also stop limiting the execution only from the
main branch (to facilitate e.g. tests from PRs) and, finally, remove
the async clause, which is not needed, since by default BK steps are
run in parallel.

.buildkite/scripts/common/trigger-pipeline-generate-steps.sh

@@ -47,16 +47,14 @@ for BRANCH in $BRANCHES; do
     cat >>pipeline_steps.yaml <<EOF
   - trigger: $PIPELINE_TO_TRIGGER
     label: ":testexecute: Triggering ${PIPELINE_TO_TRIGGER} / ${BRANCH}"
-    branches: "main"
-    async: true
     build:
       branch: "$BRANCH"
-      message: ":testexecute: Triggering ${PIPELINE_TO_TRIGGER} / ${BRANCH}"
+      message: ":testexecute: Scheduled build for ${BRANCH}"
 EOF
 done
 
 echo "--- Printing generated steps"
 yq . pipeline_steps.yaml
 
 echo "--- Uploading steps to buildkite"
-cat pipeline_steps.yml | buildkite-agent pipeline upload
+cat pipeline_steps.yaml | buildkite-agent pipeline upload

.buildkite/trigger_pipeline.yml

@@ -2,4 +2,4 @@
 
 steps:
   - label: ":pipeline: Generate trigger steps for $PIPELINE_TO_TRIGGER"
-    command: ".buildkite/scripts/trigger-pipeline-generate-steps.sh"
+    command: ".buildkite/scripts/common/trigger-pipeline-generate-steps.sh"