Fix: Invalid CQN error during draftActivate on deeply nested entities

[PujaDeshmukh17]

Problem: During draftActivate on entities with deeply nested compositions (5+ levels deep or many compositions), the following error was thrown:

Invalid CQN: Element 'SDM_READONLY_CONTEXT.uploadStatus' does not exist

The internal SDM_READONLY_CONTEXT wrapper key — used to preserve uploadStatus across handler phases — was being removed using plain Map.values() traversal. This traversal cannot reach all composition data in deeply nested CDS structures, leaving stale entries that caused CQN validation failures.

This PR contains the changes done in release 1.9.3 (#563) and is raised to port those changes to current develop.

1. Single tenant integration test: https://github.com/cap-java/sdm/actions/runs/32124371786
2. Multi tenant integration test: https://github.com/cap-java/sdm/actions/runs/32149101831

Type of change

Please delete options that are not relevant.

• 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 not work as expected)
• This change requires a documentation update

Checklist before requesting a review

• I follow Java Development Guidelines for SAP
• I have tested the functionality on my cloud environment.
• I have provided sufficient automated/ unit tests for the code.
• I have increased or maintained the test coverage.
• I have ran integration tests on my cloud environment.
• I have validated blackduck portal for any vulnerability after my commit.

Upload Screenshots/lists of the scenarios tested

• I have Uploaded Screenshots or added lists of the scenarios tested in description