chore: add partition map info if a new region is a new partition (#34095)

### Issue # (if applicable)

### Reason for this change

Add more information to the register new region issue template

### Description of changes

There's a missing step to add partition map information for a region that's in a new partition

### Describe any new or updated permissions being added

N/A

### Description of how you validated changes

N/A

### Checklist
- [ ] 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)

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

Author: GavinZZ

.github/ISSUE_TEMPLATE/region.yml

@@ -83,4 +83,5 @@ body:
         * [ ] Add region and ARN in [ADOT_LAMBDA_LAYER_PYTHON_SDK_ARNS](https://github.com/aws/aws-cdk/blob/v2.65.0/packages/@aws-cdk/region-info/build-tools/fact-tables.ts#L768) for most recent version in `x86_64` and `arm64`.
         * [ ] Add region and ARN in [ADOT_LAMBDA_LAYER_GENERIC_ARNS](https://github.com/aws/aws-cdk/blob/v2.65.0/packages/@aws-cdk/region-info/build-tools/fact-tables.ts#L847) for most recent version in `x86_64` and `arm64`.
         * [ ] Add region in [AWS_REGIONS_AND_RULES](https://github.com/aws/aws-cdk/blob/v2.65.0/packages/@aws-cdk/region-info/lib/aws-entities.ts).
+        * [ ] Add partition info if the region is also a new partition in [PARTITION_MAP](https://github.com/aws/aws-cdk/blob/main/packages/aws-cdk-lib/region-info/build-tools/fact-tables.ts#L88)
         * [ ] Run integ tests and update snapshots