[GHA] Samples tests refactoring

[mryzhov]

Optimized the samples testing in CI pipelines by reusing already converted models, addressing the bottleneck caused by the time-consuming conversion step:

• Wrapped c++/python samples calls to the pytest fixtures
• Added test labels to be able to test only c++/python or tests for specific model types only
• Replaced the large models with smaller ones.
• added an option to cleanup models and cache during the tests --cleanup-cache (it is disabled by default)

[ilya-lavrenov]

we have tests requirements here https://github.com/openvinotoolkit/openvino.genai/blob/master/tests/python_tests/requirements.txt

[mryzhov]

1. we don't need to install all of them
2. we don't have this file when install the wheel, will need to additionally checkout it.
3. it would be better to split test requirements by groups and manage them in toml file