chore: remove github copilot placeholder from pr template

https://githubnext.com/copilot-for-prs-sunset

.github/pull_request_template.md

@@ -1,9 +1,6 @@
 Fixes <issue-or-jira-number>
 
-<!-- Make sure to target release-52 branch if this PR is intended to fix the issues for the release candidate. -->
-
-## Summary
-copilot:summary
+<!-- Make sure to target release-5[0-9] branch if this PR is intended to fix the issues for the release candidate. -->
 
 ## PR Checklist
 Please convert it to a draft if any of the following conditions are not met. Reviewers may skip over until all the items are checked: