workflows: fix cockroach-microbench-ci step failing

There were errors during the push step of staging and master github
actions branch. Since both are push step, the jobs are trying to upload
the results in both cases which is duplicated data. Also
`GITHUB_HEAD_REF` doesn't work in cases of push step.

Fixes in this change:
1. Add `staging` branch into the skip comparison part.
2. Use `GITHUB_REF` rather than `GITHUB_HEAD_REF`.

Epic: none

Release note: None

.github/workflows/github-actions-essential-ci.yml

@@ -369,6 +369,7 @@ jobs:
           
           # Set the latest commit hash as an output variable
           echo "::set-output name=latest_commit::$LATEST_COMMIT"
+        if: ${{ github.event_name != 'push' }}
       - uses: actions/checkout@v4
         with:
           ref: ${{ github.event.pull_request.head.sha || github.ref }}
@@ -380,11 +381,11 @@ jobs:
         run: ./build/github/cockroach-microbench-ci.sh
         env:
           COMPARE_THRESHOLD: "5.00"
-          PUSH_STEP: ${{ github.event_name == 'push' }}
+          PUSH_STEP: ${{ github.event_name == 'push' && env.GITHUB_ACTIONS_BRANCH != 'staging' }}
           BASE_SHA: ${{ steps.get_latest_commit_target_branch.outputs.latest_commit }}
 
           # TODO(sambhav-jain-16): add Performance note check and use this flag. Currently set to false (https://github.com/cockroachdb/cockroach/issues/106661)
-          SKIP_COMPARISON: false
+          SKIP_COMPARISON: ${{ env.GITHUB_ACTIONS_BRANCH == 'staging' }}
       - name: upload build results
         run: ./build/github/summarize-build.sh bes.bin
         if: always()

build/github/cockroach-microbench-ci.sh

@@ -53,8 +53,8 @@ $roachprod_microbench_dir/roachprod-microbench clean "$log_output_file_path" "$c
 
 # Push artifact if this is a base merge and skip comparison
 if $PUSH_STEP; then
-  gcloud storage cp "$cleaned_current_dir/$benchmark_file_name" "$storage_bucket_url/$GITHUB_HEAD_REF/$GITHUB_SHA.log"
-  echo "Skipping comparison since this is a base merge."
+  gcloud storage cp "$cleaned_current_dir/$benchmark_file_name" "$storage_bucket_url/$GITHUB_REF/$GITHUB_SHA.log"
+  echo "Skipping comparison since this is a push step into the target branch"
   exit $success_exit_status
 fi