[Identity] Adjust flaky tests

[pvaneck]

In some pipeline runs, over a second may elapse between when a credential is created and when a token request is made. This causes flakiness in the test_cached_token_outside_refresh_window tests. This change increases the time window.

Example failure message:

================================== FAILURES ===================================
__________ test_cached_token_outside_refresh_window[get_token_info] ___________

get_token_method = 'get_token_info'

    @pytest.mark.parametrize("get_token_method", GET_TOKEN_METHODS)
    def test_cached_token_outside_refresh_window(get_token_method):
        """A credential shouldn't request a new token when it has a cached one with sufficient validity remaining"""
    
        credential = MockCredential(
            cached_token=AccessTokenInfo(CACHED_TOKEN, int(time.time() + DEFAULT_REFRESH_OFFSET + 1))
        )
        token = getattr(credential, get_token_method)(SCOPE)
    
        credential.acquire_token_silently.assert_called_once_with(SCOPE, claims=None, enable_cae=False, tenant_id=None)
>       assert credential.request_token.call_count == 0
E       AssertionError: assert 1 == 0
E        +  where 1 = <Mock id='2862391543040'>.call_count
E        +    where <Mock id='2862391543040'> = <test_get_token_mixin.MockCredential object at 0x0000029A73D4DFA0>.request_token

[Copilot]

Pull Request Overview

This PR addresses intermittent failures in the cached-token tests by extending the validity buffer before a refresh is triggered.

• Increases the time buffer in both async and sync tests from DEFAULT_REFRESH_OFFSET + 1 to DEFAULT_REFRESH_OFFSET + 10.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
sdk/identity/azure-identity/tests/test_get_token_mixin_async.py	Extended cached token offset from + 1 to + 10 to reduce flakiness
sdk/identity/azure-identity/tests/test_get_token_mixin.py	Same change for the synchronous test