Use a shorter format for the git logs shown on Phabricator.

The current output can make the page of a diff very long.

---

Migrated from D2934 (view on Phabricator)

jobs/templates/includes/stage-apply-phabricator-diff.groovy.j2

@@ -48,7 +48,7 @@ stage('Apply phabricator diff') {
             echo "===== Changes applied before test ====="
             echo
             echo '```'
-            git log ${ORIGINAL_TAG}..
+            git log --format=oneline ${ORIGINAL_TAG}..
             echo '```'
         else
             echo '**Attempts to apply the diff failed!**'