Fix operator precedence on evicted-session close timeout

[genisis0x]

What was wrong?

HTTPSessionManager.cache_and_return_session (sync) and async_cache_and_return_session (async) schedule a close-evicted-sessions task to fire after the in-flight request would have timed out, plus a small 0.1s slack so any request that started right before the eviction has time to finish before the underlying session is closed.

Both call sites used:

# sync, web3/_utils/http_session_manager.py:99
request_timeout or DEFAULT_HTTP_TIMEOUT + 0.1
# async, web3/_utils/http_session_manager.py:271
request_timeout.total or DEFAULT_HTTP_TIMEOUT + 0.1

+ binds tighter than or in Python, so the expression actually parses as request_timeout or (DEFAULT_HTTP_TIMEOUT + 0.1). The intended + 0.1 slack only applied when the caller fell back to the default. Any caller that supplied a non-default timeout (e.g. request_timeout=5) had its close timer fire at exactly 5.0s, racing the in-flight request:

>>> request_timeout = 5
>>> DEFAULT_HTTP_TIMEOUT = 30
>>> request_timeout or DEFAULT_HTTP_TIMEOUT + 0.1
5
>>> (request_timeout or DEFAULT_HTTP_TIMEOUT) + 0.1
5.1

The comments above each call site already describe the intended behavior (wait over the default timeout / bit more than the request_timeout).

How was it fixed?

Parenthesize the or so the slack is always applied to the chosen timeout:

(request_timeout or DEFAULT_HTTP_TIMEOUT) + 0.1

Same change in both the sync and async paths.

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Type of change

• Bug fix (non-breaking change which fixes an issue)

Test plan

Added focused regression tests in tests/core/utilities/test_http_session_manager.py:

• test_session_manager_evicted_close_timer_uses_request_timeout_plus_slack — patches threading.Timer, fills a 1-entry cache, and asserts the captured interval is request_timeout + 0.1.
• test_session_manager_evicted_close_timer_falls_back_to_default — same path with request_timeout=None, asserts the interval is DEFAULT_HTTP_TIMEOUT + 0.1.
• test_async_evicted_close_task_uses_request_timeout_plus_slack — async equivalent that patches _async_close_evicted_sessions and asserts it was scheduled with ClientTimeout.total + 0.1.

The pre-existing test_async_session_manager_cache_does_not_close_session_before_call already exercised the async eviction path and continues to pass with the change (it waited for _timeout + 0.1 regardless and is not sensitive to the bug).