.github: fix workflow settings and allow branch pushes to main by committers (#6225)

This fixes the comment message for merge conflict checker and resets the
github branch protection for main in case of need by the RM.

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

Author: yadvr

.asf.yaml

@@ -46,7 +46,4 @@ github:
   collaborators:
     - acs-robot
 
-  #protected_branches:
-  #  main:
-  #    required_pull_request_reviews:
-  #      required_approving_review_count: 2
+  protected_branches: ~

.github/workflows/merge-conflict-checker.yml

@@ -18,12 +18,8 @@
 name: "Check Pull Requests Conflict"
 on:
   push:
-    branches:
-      - main
-  pull_request:
+  pull_request_target:
     types: [synchronize]
-    branches:
-      - main
 
 jobs:
   triage:
@@ -36,4 +32,4 @@ jobs:
         dirtyLabel: "status:has-conflicts"
         removeOnDirtyLabel: "status:ready-for-review"
         continueOnMissingPermissions: true
-        commentOnDirty: "Hi @${author}, your pull request has merge conflicts. Can you fix the conflicts and sync your branch with the base branch?"
+        commentOnDirty: "Hi @${{ github.event.pull_request.user.login }}, your pull request has merge conflicts. Can you fix the conflicts and sync your branch with the base branch?"