LT-22361: Rename 'master' branch to 'main'

and close 'develop' and 'release/*' branches.

Continuing to build pushes and PRs to release branches
as a way to stabilize a release while the next sprint continues.

Author: papeh

.github/workflows/CI.yml

@@ -1,9 +1,9 @@
 name: Flex CI
 on:
   push:
-    branches: ["release/**", "develop", "master", "feature/PubSub"]
+    branches: ["release/**", "main", "feature/PubSub"]
   pull_request:
-    branches: ["release/**", "develop", "master", "feature/PubSub"]
+    branches: ["release/**", "main", "feature/PubSub"]
   workflow_dispatch:
 
 concurrency: