Improve Pytest environment handling in `Actor._get_default_exit_process`

[vdusek]

Description

Method Actor._get_default_exit_process currently contains the following logic:

# Check if running in Pytest by detecting the relevant environment variable.
if os.getenv('PYTEST_CURRENT_TEST'):
    self.log.debug('Running in Pytest, setting default `exit_process` to False.')
    return False

This behavior is incorrect - production code should not adjust its defaults based on test environment detection. The logic should be inverted: instead of the SDK adapting to Pytest during normal execution, the test environment should explicitly configure the exit_process flag as needed.

Expected fix:

• Remove the Pytest-specific condition from the production code.
• Handle exit_process=False setup within the test environment (e.g., via test fixtures or explicit configuration).