fix(cloudfront): make long function name deterministic (#30392)

### Issue # (if applicable)

Closes #20017 as well as #15523 and #28629 

### Reason for this change

Due to the way function names are generated using token strings with either single- or double-digit numbers, longer function names can be truncated differently, leading to inconsistency in generated CloudFormation templates.

### Description of changes

To ensure backwards compatibility, if names are longer than 64 characters and use region tokens, if the token uses a single-digit region number, it takes the first **31** characters + the last 32 characters; if the token uses a double-digit region number or otherwise, it takes the first **32** characters + the last 32 characters. This ensures it will always take the same first chunk of the actual function's name.

### Description of how you validated changes

A new unit test was added to verify the consistency of function names in the template.

### 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*

packages/@aws-cdk-testing/framework-integ/test/aws-cloudfront/test/integ.distribution-function-runtime.js.snapshot/integ-distribution-function.template.json

@@ -6,10 +6,10 @@
     "AutoPublish": true,
     "FunctionCode": "function handler(event) { return event.request }",
     "FunctionConfig": {
-     "Comment": "eu-west-1integdistributionfunctionFunctionRequest8E65DEEB",
+     "Comment": "eu-west-1integ-distributinFunctionRequest8E65DEEB",
      "Runtime": "cloudfront-js-1.0"
     },
-    "Name": "eu-west-1integdistributionfunctionFunctionRequest8E65DEEB"
+    "Name": "eu-west-1integ-distributinFunctionRequest8E65DEEB"
    }
   },
   "FunctionResponse4EF2D1D3": {
@@ -18,10 +18,10 @@
     "AutoPublish": true,
     "FunctionCode": "function handler(event) { return event.response }",
     "FunctionConfig": {
-     "Comment": "eu-west-1integdistributionfunctionFunctionResponseDD4BADA1",
+     "Comment": "eu-west-1integ-distributiFunctionResponseDD4BADA1",
      "Runtime": "cloudfront-js-2.0"
     },
-    "Name": "eu-west-1integdistributionfunctionFunctionResponseDD4BADA1"
+    "Name": "eu-west-1integ-distributiFunctionResponseDD4BADA1"
    }
   },
   "DistB3B78991": {

packages/@aws-cdk-testing/framework-integ/test/aws-cloudfront/test/integ.distribution-function.js.snapshot/integ-distribution-function.template.json

@@ -3,13 +3,13 @@
   "Function76856677": {
    "Type": "AWS::CloudFront::Function",
    "Properties": {
-    "Name": "eu-west-1integdistributionfunctionFunctionDCD62A02",
     "AutoPublish": true,
     "FunctionCode": "function handler(event) { return event.request }",
     "FunctionConfig": {
      "Comment": "eu-west-1integdistributionfunctionFunctionDCD62A02",
      "Runtime": "cloudfront-js-1.0"
-    }
+    },
+    "Name": "eu-west-1integdistributionfunctionFunctionDCD62A02"
    }
   },
   "DistB3B78991": {