Remove old interpreted endpoint rules path, merge rules2 into rules, and delete legacy runtime resources

[S-Saranya1]

Motivation and Context

This PR completes the cleanup for enabling compiled endpoint rules as the only code path. With the flag-flip PR enabling compiled rules for all services, the old interpreted endpoint rules path and the separate rules2 package are no longer needed. This PR removes the legacy code and consolidates everything into a single clean structure.

This PR is part of 3 cleanup PRs:

• Config cleanup PR (Remove enableGenerateCompiledEndpointRules entries from all customization.config files #7268): Removes enableGenerateCompiledEndpointRules entries from all service customization.config files
• This PR: Removes the flag entirely from codegen, deletes the old interpreted code path, and merges the rules2 package into rules
• Service changes PR: Migrates STS/S3 source code off deprecated internal classes and removes old rule engine tests

Modifications

• Remove the enableGenerateCompiledEndpointRules flag — Delete field, getter, and setter from CustomizationConfig.java
• Remove if/else branching in EndpointProviderTasks.java — Always use compiled path, remove shouldGenerateCompiledEndpointRules() and generateDefaultProvider() methods
• Delete old interpreted endpoint provider — Remove EndpointProviderSpec.java (the interpreted code generator)
• Delete RulesEngineRuntimeLiteGeneratorTask.java and RulesEngineRuntimeGeneratorTask2.java — No longer needed; the base RulesEngineRuntimeGeneratorTask now handles all resource copying
• Merge rules2/ package into rules/ — Move all files, update package statements, rename EndpointProviderSpec2 → EndpointProviderSpec
• Delete old interpreted .java.resource files — Remove 54 files (DefaultRuleEngine, RuleEvaluator, Condition, Expr, etc.) that were only used by the interpreted path
• Delete Arn.java.resource — No longer needed (internal teams will migrate to the public software.amazon.awssdk.arns.Arn)
• Delete RuleSetCreationSpec.java — Dead code, not referenced anywhere
• Remove rulesEngineResourceFiles2() from EndpointRulesSpecUtils.java
• Delete EndpointProviderClassSpecTest.java — Tested the old interpreted provider which no longer exists
• Move test files and resources from rules2/ to rules/

Testing

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license

[S-Saranya1]

note: Builds are failing because this PR depends on the flag-flip PR (#7265) which has the regionId bug fix. Once that's merged first, the builds here will pass.