gitlab_merge: add commit history to merge script
This script is used in our GAUDI and ACTS nightlies to merge additional MRs on top of the current branch. Add a printout of the commit history to make the builds more easily reproducible.
Example printout:
gitlab_merge.sh> Merging atlas/athena!63853 with label matching nightly:ACTS
From https://gitlab.cern.ch:8443/atlas/athena
* [new ref] refs/merge-requests/63853/head -> mr-upstream-63853
Merge made by the 'ort' strategy.
Deleted branch mr-upstream-63853 (was 78528ac979e).
gitlab_merge.sh> Commit history of this build:
2a9578dceef (HEAD) Merge branch 'mr-upstream-63853' into HEAD
78528ac979e Merge branch 'fixes' into 'canary'
f86622837d2 Neutral removed
e006c2459f4 Fix for https://github.com/acts-project/acts/pull/2269
e03c83faf18 (upstream/main) Merge branch 'adye-ckf23' into 'main'Relates to ATLINFR-4967.