Update Gerrit 3.8 to 3.8.5 and 3.9 to 3.9.4

This updates our production 3.8 image to the latest bugfix release and
our future upgrade image to 3.9.4. Importantly this addresses problems
with reindexing in 3.9 which will allow us to start upgrade testing in
earnest.

Change-Id: I21f692121665d5630b68c17901b80fc3102ea280

zuul.d/docker-images/gerrit.yaml

@@ -62,11 +62,11 @@
         override-checkout: stable-3.8
       # Backend behavior plugins
       - name: gerrit.googlesource.com/plugins/commit-message-length-validator
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
       - name: gerrit.googlesource.com/plugins/delete-project
         override-checkout: stable-3.8
       - name: gerrit.googlesource.com/plugins/hooks
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
       - name: gerrit.googlesource.com/plugins/its-base
         # There is no 3.8 branch
         override-checkout: master
@@ -74,29 +74,29 @@
         # There is no 3.8 branch
         override-checkout: master
       - name: gerrit.googlesource.com/plugins/plugin-manager
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
       - name: gerrit.googlesource.com/plugins/replication
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
       - name: gerrit.googlesource.com/plugins/reviewnotes
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
       - name: gerrit.googlesource.com/plugins/singleusergroup
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
       - name: gerrit.googlesource.com/plugins/webhooks
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
       # UI behavior plugins
       - name: gerrit.googlesource.com/plugins/codemirror-editor
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
       - name: gerrit.googlesource.com/plugins/download-commands
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
       - name: gerrit.googlesource.com/plugins/gitiles
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
       - name: gerrit.googlesource.com/plugins/zuul-results-summary
         override-checkout: main
       # Non plugin submodules
       - name: gerrit.googlesource.com/jgit
         override-checkout: master
       - name: gerrit.googlesource.com/polymer-bridges
-        override-checkout: v3.8.4
+        override-checkout: v3.8.5
     vars: &gerrit_vars_3_8
       docker_images:
         - context: docker/gerrit/bazel
@@ -154,11 +154,11 @@
         override-checkout: stable-3.9
       # Backend behavior plugins
       - name: gerrit.googlesource.com/plugins/commit-message-length-validator
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
       - name: gerrit.googlesource.com/plugins/delete-project
-        override-checkout: v3.9.1
+        override-checkout: stable-3.9
       - name: gerrit.googlesource.com/plugins/hooks
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
       - name: gerrit.googlesource.com/plugins/its-base
         # There is no 3.9 branch
         override-checkout: master
@@ -166,22 +166,22 @@
         # There is no 3.9 branch
         override-checkout: master
       - name: gerrit.googlesource.com/plugins/plugin-manager
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
       - name: gerrit.googlesource.com/plugins/replication
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
       - name: gerrit.googlesource.com/plugins/reviewnotes
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
       - name: gerrit.googlesource.com/plugins/singleusergroup
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
       - name: gerrit.googlesource.com/plugins/webhooks
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
       # UI behavior plugins
       - name: gerrit.googlesource.com/plugins/codemirror-editor
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
       - name: gerrit.googlesource.com/plugins/download-commands
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
       - name: gerrit.googlesource.com/plugins/gitiles
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
       - name: gerrit.googlesource.com/plugins/zuul-results-summary
         override-checkout: main
       # Non plugin submodules
@@ -190,7 +190,7 @@
       - name: gerrit.googlesource.com/jgit
         override-checkout: master
       - name: gerrit.googlesource.com/polymer-bridges
-        override-checkout: v3.9.1
+        override-checkout: v3.9.4
     vars: &gerrit_vars_3_9
       docker_images:
         - context: docker/gerrit/bazel