Enable Gerrit JWT service for buildbucket & tricium plugins

Change-Id: I1fbaaf980cb868a6f6d2ffa1566e5eb3e8eb56fa
Reviewed-on: https://boringssl-review.googlesource.com/c/All-Projects/+/52805
Reviewed-by: Gavin Mak <gavinmak@google.com>

project.config

diff --git a/project.config b/project.config
index 954ec5b..abd2587 100644
--- a/project.config
+++ b/project.config
@@ -196,3 +196,5 @@
         submittableIf = label:Code-Review=MAX,user=non_uploader AND -label:Code-Review=MIN
         overrideIf = label:Bot-Commit=+1
         canOverrideInChildProjects = true
+[plugin "jwtservice"]
+  audience = "https://api.cr.dev"