[hoganbr-amzn]

Issue #, if available: Fixes #4981

Description of changes:

This PR is stacked on #4980 (and through it on #4976 and #4978) and shows their commits until they merge; the change here is the last commit. It needs get_partition from #4980.

Conditions.build_scenerios_on_region decides an Fn::Equals between Ref AWS::Region and a literal for the region being linted. An Fn::Equals against Ref AWS::Partition stays [True, False], even though the region fixes the partition. So E3006 reports a resource as missing from a region where its condition can never be true:

Conditions:
  IsCommercial: !Equals [!Ref AWS::Partition, aws]
Resources:
  Accelerator:
    Type: AWS::GlobalAccelerator::Accelerator
    Condition: IsCommercial
    Properties:
      Name: example

cfn-lint --regions us-east-1 cn-north-1 us-gov-west-1 on main:

E3006 Resource type 'AWS::GlobalAccelerator::Accelerator' does not exist in 'cn-north-1'
E3006 Resource type 'AWS::GlobalAccelerator::Accelerator' does not exist in 'us-gov-west-1'

With this change neither is reported. The same resource gated on !Equals [aws-cn, !Ref AWS::Partition] still gets E3006 for cn-north-1.

Equal gains an is_partition property, computed by the same helper as is_region. build_scenerios_on_region decides those equals from get_partition(region) (added in #4980). Only literal comparisons are decided: !Equals [!Ref AWS::Partition, !Ref SomeParameter] stays undecided.

Reach. build_scenerios_on_region is called by E3006 and by Conditions.build_scenarios when it is given a region. No other bundled rule passes a region, so E3006 is the only rule whose output changes. It can only drop findings, in regions where a partition condition is false. The context-path conditions (cfnlint.context.conditions) are unchanged; their is_region has no caller outside that package, so Fn::If resolution is not affected.

Verification.

• test_equals.py: Equal recognises Ref AWS::Partition on either side and leaves region and parameter equals alone.
• test_conditions.py: the region decides the partition equals, including under Fn::Not, Fn::And and Fn::Or and combined with a region equals, while parameter conditions stay undecided.
• test_type.py: E3006 run on a decoded template (not a mocked conditions) with a partition condition reports only the region where the condition holds.
• All three fail without this change.
• Good fixtures linted one region at a time in all eight partitions (same command as fix(iam): accept IAM principal ARNs from every partition #4976): same output as without this change in every region.
• pytest test and pre-commit run --all-files pass.

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[codecov]

Codecov Report

❌ Patch coverage is 92.30769% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.80%. Comparing base (dbb3da3) to head (069935c).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/cfnlint/conditions/_equals.py	86.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4982   +/-   ##
=======================================
  Coverage   94.80%   94.80%           
=======================================
  Files         441      441           
  Lines       16128    16144   +16     
  Branches     3130     3132    +2     
=======================================
+ Hits        15290    15306   +16     
  Misses        463      463           
  Partials      375      375           

Flag	Coverage Δ
unittests	94.80% <92.30%> (+<0.01%)	⬆️

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