scripts/git: Avoid sleeping before the last push in git-push-all.sh

Change the loop order, so that we only sleep between pushes,
and avoid sleeping after all the pushes are done.

(In rare cases, there may still be an extra sleep.)

Part of 32216.

scripts/git/git-push-all.sh

@@ -315,12 +315,15 @@ else
       printf "%s\n" "$RELEASE_BRANCHES"
     fi
   fi
-  $GIT_PUSH "$@" "$UPSTREAM_REMOTE" "$MASTER_BRANCH"
-  sleep "$PUSH_DELAY"
   # shellcheck disable=SC2086
-  for b in $MAINT_BRANCHES; do
+  for b in $MASTER_BRANCH $MAINT_BRANCHES; do
     $GIT_PUSH "$@" "$UPSTREAM_REMOTE" "$b"
-    sleep "$PUSH_DELAY"
+    # If we are pushing more than one branch, delay.
+    # In the unlikely scenario where we are pushing maint without master,
+    # or maint without release, there may be an extra delay
+    if [ "$MAINT_BRANCHES" ] || [ "$RELEASE_BRANCHES" ]; then
+      sleep "$PUSH_DELAY"
+    fi
   done
   if [ "$RELEASE_BRANCHES" ]; then
     # shellcheck disable=SC2086