Toggle release flag to block any PR getting merged (#1002)

## Description
This ensures that no PR is merged during active deployment

## Testing


## Additional Notes to the Reviewer
This should be toggle back to false once the release is completed
NO_CHANGELOG=true

Signed-off-by: Nikhil Suri <nikhil.suri@databricks.com>

Author: nikhilsuri-db

development/.release-freeze.json

@@ -1,5 +1,5 @@
 {
-  "freeze": false,
-  "reason": "Release description",
+  "freeze": true,
+  "reason": "Releasing JDBC - 16th Sep",
   "allow_list": []
 }