Tweak Gitpod config (badges#3934)

This disables the comments like badges#3933 (comment) which seem a bit chatty, as the review apps can be accessed from the checks.

This and also turns off builds for branches. For the most part we keep PRs open when branches are at a stage of being ready for useful review, so I think that should be sufficient for us.

.gitpod.yml

@@ -9,15 +9,15 @@ github:
     # enable for the master/default branch (defaults to true)
     master: true
     # enable for all branches in this repo (defaults to false)
-    branches: true
+    branches: false
     # enable for pull requests coming from this repo (defaults to true)
     pullRequests: true
     # enable for pull requests coming from forks (defaults to false)
     pullRequestsFromForks: true
     # add a check to pull requests (defaults to true)
     addCheck: true
     # add a "Review in Gitpod" button as a comment to pull requests (defaults to false)
-    addComment: true
+    addComment: false
     # add a "Review in Gitpod" button to the pull request's description (defaults to false)
     addBadge: false
     # add a label once the prebuild is ready to pull requests (defaults to false)