fix(ci): disable -x flag when running upgrade tests (#11646)

It seems that the -x flag triggered an issue in the upgrade test
script, but it is not entirely clear how only the release/3.3.x
branch was affected.  Disable -x for now to make sure that we're
not seeing the problem in other branches

(cherry picked from commit 613fb31)

Co-authored-by: Hans Hübner <hans.huebner@gmail.com>

.github/workflows/upgrade-tests.yml

@@ -17,6 +17,7 @@ on:
     - master
     - release/*
     - test-please/*
+  workflow_dispatch:
 # cancel previous runs if new commits are pushed to the PR, but run for each commit on master
 concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
@@ -49,4 +50,4 @@ jobs:
 
       - name: Run upgrade tests
         run: |
-          bash -x ./scripts/upgrade-tests/test-upgrade-path.sh
+          bash ./scripts/upgrade-tests/test-upgrade-path.sh