chore(mergify): update priority for new rule (#33303)

### Issue # (if applicable)

Closes NA
### Reason for this change

Moving rule position to update the priority in order to fix freezing rules.
If a queue with high priority is frozen, the ones below it will also be under freeze as well, which is not the desired state that we want. Priority should be higher for queue rule `priority-squash` so that we can successfully freeze the default-squash one.

### Description of changes
Moving rule position to update the priority in order to fix freezing rules.

### Describe any new or updated permissions being added

NA


### Description of how you validated changes

NA

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

.mergify.yml

@@ -20,13 +20,14 @@ queue_rules:
       {{ title }} (#{{ number }})
       {{ body }}
 
-  - name: default-squash
+  - name: priority-squash
     update_method: merge
     merge_method: squash
     conditions:
       - base!=release
       - -title~=(WIP|wip)
-      - -label~=(blocked|do-not-merge|no-squash|priority-pr)
+      - -label~=(blocked|do-not-merge|no-squash)
+      - label~=priority-pr
       - -merged
       - -closed
       - "#approved-reviews-by>=1"
@@ -39,14 +40,13 @@ queue_rules:
       {{ title }} (#{{ number }})
       {{ body }}
 
-  - name: priority-squash
+  - name: default-squash
     update_method: merge
     merge_method: squash
     conditions:
       - base!=release
       - -title~=(WIP|wip)
-      - -label~=(blocked|do-not-merge|no-squash)
-      - label~=priority-pr
+      - -label~=(blocked|do-not-merge|no-squash|priority-pr)
       - -merged
       - -closed
       - "#approved-reviews-by>=1"