feat(3p/gerrit): Upgrade Gerrit and plugins to v3.4.0

Brings us back to a stable version of Gerrit instead of a random
commit. Note that Gerrit 3.4.1 is out, but due to a bug it can not be
built publicly because it accidentally points at a private
submodule (this is being fixed upstream).

Change-Id: I0376c63a649498cef999dfa99bfccba511f2c8da
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3444
Tested-by: BuildkiteCI
Reviewed-by: lukegb <lukegb@tvl.fyi>

third_party/gerrit/0001-Use-detzip-in-download_bower.py.patch

@@ -1,4 +1,4 @@
-From 6d8cfd8443bef47bfb106e2272e5e9d86c1fd291 Mon Sep 17 00:00:00 2001
+From 621cadcc1dd71e9397c21cf8cf0f1aae4f6f7057 Mon Sep 17 00:00:00 2001
 From: Luke Granger-Brown <git@lukegb.com>
 Date: Thu, 2 Jul 2020 23:02:09 +0100
 Subject: [PATCH 1/7] Use detzip in download_bower.py
@@ -8,10 +8,10 @@ Subject: [PATCH 1/7] Use detzip in download_bower.py
  1 file changed, 1 insertion(+), 1 deletion(-)
 
 diff --git a/tools/js/download_bower.py b/tools/js/download_bower.py
-index 1df4b826bc..65bda74082 100755
+index d541b565a9..ffdae60f95 100755
 --- a/tools/js/download_bower.py
 +++ b/tools/js/download_bower.py
-@@ -106,7 +106,7 @@ def main():
+@@ -110,7 +110,7 @@ def main():
                  args.b, '--quiet', 'install', '%s#%s' % (args.p, args.v)))
          bc = os.path.join(cwd, 'bower_components')
          subprocess.check_call(
@@ -21,5 +21,5 @@ index 1df4b826bc..65bda74082 100755
  
          if args.s:
 -- 
-2.29.2
+2.32.0