tails.git post-receive hook: notify Jenkins using the Git remote URL it's using

We changed the Jenkins configuration to pull from GitLab while the mirroring to
Gitolite was not working:

  tails/jenkins-jobs@4db52b22

But we did not adjust this post-receive hook accordingly,
so the "pushing to Git triggers a Jenkins build" behavior
is broken.

Let's repair this, until we make up our mind (tails/sysadmin#17715)
wrt. whether we should keep pointing Jenkins to GitLab's tails/tails,
or use the local mirror we have on puppet-git.lizard.

templates/gitolite/hooks/tails-post-receive.erb

@@ -3,7 +3,7 @@
 set -eu
 
 JENKINS_MASTER_URL='http://jenkins.<%= @domain %>:8080'
-GIT_REMOTE='gitolite3@<%= @fqdn %>'
+GIT_REMOTE='https://gitlab.tails.boum.org/tails/tails.git'
 
 NOTIFY_JENKINS=no
 
@@ -36,7 +36,7 @@ done
 
 if [ "$NOTIFY_JENKINS" = yes ]; then
     echo "| Notifying Jenkins of Git updates..."
-    exec curl --silent --show-error "${JENKINS_MASTER_URL}/git/notifyCommit?url=${GIT_REMOTE}:tails" 2>&1 \
+    exec curl --silent --show-error "${JENKINS_MASTER_URL}/git/notifyCommit?url=${GIT_REMOTE}" 2>&1 \
     | perl -p -E 's,^,| ,'
 fi