[TT-7489/TT-9576]refactor TestTransformResponseBody to res_handler_transform.go.

[jeffy-mathew]

improve ResponseTransformMiddleware_Enabled.

Description

https://tyktech.atlassian.net/browse/TT-9576

Related Issue

Motivation and Context

How This Has Been Tested

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring or add test (improvements in base code or adds test coverage to functionality)

Checklist

• I ensured that the documentation is up to date
• I explained why this PR updates go.mod in detail with reasoning why it's required
• I would like a code coverage CI quality gate exception and have explained why

[Tyk-ITS]

API tests result: success ✅
Branch used: refs/pull/5352/merge
Commit: edbcf5b
Triggered by: pull_request (@jeffy-mathew)
Execution page

[Tyk-ITS]

API tests result: success ✅
Branch used: refs/pull/5352/merge
Commit:
Triggered by: pull_request (@jeffy-mathew)
Execution page

[Tyk-ITS]

API tests result: success ✅
Branch used: refs/pull/5352/merge
Commit: 9b8ad82
Triggered by: pull_request (@jeffy-mathew)
Execution page

[sonarcloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

100.0% Coverage
0.0% Duplication

Catch issues before they fail your Quality Gate with our IDE extension SonarLint

[Tyk-ITS]

API tests result: success ✅
Branch used: refs/pull/5352/merge
Commit: 98e9ca3
Triggered by: pull_request (@jeffy-mathew)
Execution page