[CICD] Upload unittest coverage report to FlagCICD platform && Access FlagCICD runner (#58)
Description
Simplifies and consolidates the coverage report generation logic in the
CI unittest workflow, reducing redundant steps and dependencies.
Need to test uploading reports to FlagCICD step in CI env.
Type of change

 New feature (non-breaking change which adds functionality)
 Infra/Build change (changes to CI/CD workflows or build scripts)
 Code refactoring
 Documentation change
 Bug fix
 Breaking change

Changes

Merged Generate Coverage Report into the Execute Tests step —
coverage combine and json generation now run inline after bash test.sh, following the same pattern as Megatron-LM-FL
Coverage collection is gated on test_type == 'unittest' to avoid
running for lint/debug groups, and pip install is done only once
Removed fetch-depth: 0 from checkout steps (not required for unit
test runs)
Removed unused/leftover scripts from the repository

TODO
Checklist:

 I have read and followed the contributing guidelines.
 The functionality is complete
 I have commented my code, particularly in coverage report
uploading steps
 My changes generate no new warnings
 I have added/updated tests that prove my feature works on Cuda and
Metax platform.
 New and existing unit tests pass locally on Cuda and Metax
platform.