fix: resolve merge conflicts for file_search attributes backport

[are-ces]

What does this PR do?

Resolves merge conflicts in the backport of file_search attributes fix to release-0.3.x.

Test Plan

uv run pytest tests/unit/providers/agents/meta_reference/test_openai_responses.py -v

All 23 tests pass.

[are-ces]

I removed the tests which came along with the backport (which were not supposed to be in 0.3.x)

[leseb]

why not target the release branch directly instead of the merfigy branch?

[are-ces]

Not sure how that works, how do you bring those changes to this pr?

[are-ces]

Btw I don't think the pre-commit issues depend on this pr:

Distribution Template Codegen................................................Failed
- hook id: distro-codegen
- exit code: 1

warning: `VIRTUAL_ENV=/Users/cpompeia/.cache/pre-commit/repo2cmpd0mc/py_env-python3.12` does not match the project environment path `.venv` and will be ignored; use `--active` to target the active environment instead
⠋ Processing distribution templates...
Traceback (most recent call last):
  File "/Users/cpompeia/Documents/Dev/llama-stack-latest/llama-stack/./scripts/distro_codegen.py", line 128, in <module>
    main()
  File "/Users/cpompeia/Documents/Dev/llama-stack-latest/llama-stack/./scripts/distro_codegen.py", line 106, in main
    pre_import_distros(distro_dirs)
  File "/Users/cpompeia/Documents/Dev/llama-stack-latest/llama-stack/./scripts/distro_codegen.py", line 92, in pre_import_distros
    importlib.import_module(module_name)
  File "/Users/cpompeia/.local/share/uv/python/cpython-3.12.11-macos-aarch64-none/lib/python3.12/importlib/__init__.py", line 90, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1387, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1324, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'llama_stack.distributions.postgres-demo'

Provider Codegen.............................................................Failed
- hook id: provider-codegen
- exit code: 1

warning: `VIRTUAL_ENV=/Users/cpompeia/.cache/pre-commit/repo2cmpd0mc/py_env-python3.12` does not match the project environment path `.venv` and will be ignored; use `--active` to target the active environment instead
Traceback (most recent call last):
  File "/Users/cpompeia/Documents/Dev/llama-stack-latest/llama-stack/./scripts/provider_codegen.py", line 16, in <module>
    from llama_stack.core.distribution import get_provider_registry
ModuleNotFoundError: No module named 'llama_stack.core.distribution'

API Spec Codegen.............................................................Passed
Check GitHub Actions use SHA-pinned actions..................................Passed
Check for missing __init__.py files..........................................Failed
- hook id: check-init-py
- exit code: 1

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