Workaround to avoid a hard shutdown when testing the release

When running the release on a Docker container with Debian, the
start-stop-daemon is not able to send the HUP signal to the Gerrit JVM,
causing the shutdown of the server with a KILL signal.

Ending the JVM execution following a KILL does not respect the
operations triggered during the shutdown sequence, including also the
flushing of Lucene in-memory data.

The result of using start-stop-daemon is therefore the disappearance of
the changes created just before the shutdown, which was making the
gerrit-upgrade-test.sh fail.

Bug: Issue 450577969
Change-Id: Ia2c6bac3f1d8ed798a277f4e78e2cf29b627d7b3

Author: lucamilanesio

jenkins-docker/agent-release/gerrit-upgrade-test.sh

@@ -23,6 +23,11 @@ export gerritReleasesUrl=https://gerrit-releases.storage.googleapis.com
 export previousVersionWar=gerrit-$1.war
 export nextVersionWar=gerrit-$2.war
 
+# Disable the use of start-stop-daemon because of the inability to stop
+# Gerrit gracefully when running it on Docker.
+# See Issue 450577969
+export START_STOP_DAEMON=0
+
 function downloadGerritWar
 {
   if checkWar $1