fix(scrapy): async-thread shutdown, duplicate error logs, and timeout setting

[vdusek]

Fixes several smaller defects in the Scrapy integration's background event-loop thread, scheduler, and HTTP cache storage.

• HTTP cache cleanup could leak the event-loop thread. In ApifyCacheStorage.close_spider, the expiration sweep ran outside the try, so a failure there skipped AsyncThread.close(). The sweep now runs inside try, with close() in a finally so it always runs.
• AsyncThread.close() raised on a second call. A repeated close (e.g. ApifyScheduler.open() closing on failure, then Scrapy closing again) called into the already-closed loop and raised RuntimeError: Event loop is closed. Added an is_closed() early-return guard so a second close is a no-op.
• AsyncThread.close() ignored its timeout argument for the task-cancellation step (it used the constructor default). It now passes the caller's timeout to that step too.
• run_coro timeout left the coroutine running. On timeout it now cancels the future so the coroutine does not outlive the timeout.
• Scheduler errors were reported 2–3×. run_coro logged-and-raised and each scheduler call added traceback.print_exc() (which bypasses ActorLogFormatter), on top of Scrapy's own logging. Removed the redundant traceback.print_exc() wrappers and run_coro's log-and-raise; errors now surface once, formatted, via Scrapy.
• refactor(scrapy): make AsyncThread timeout configurable #955's configurable timeout was unreachable by users. Added the APIFY_ASYNC_THREAD_TIMEOUT_SECS Scrapy setting, wired into the scheduler (via from_crawler) and the cache storage so the AsyncThread timeout is actually configurable.

Adds unit tests for each fix (new tests/unit/scrapy/test_async_thread.py plus additions to the scheduler and HTTP cache test modules).

[codecov]

Codecov Report

❌ Patch coverage is 77.27273% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.01%. Comparing base (0daca28) to head (50aa539).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/apify/scrapy/extensions/_httpcache.py	72.22%	15 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #980      +/-   ##
==========================================
+ Coverage   89.90%   91.01%   +1.10%     
==========================================
  Files          49       49              
  Lines        3091     3116      +25     
==========================================
+ Hits         2779     2836      +57     
+ Misses        312      280      -32     

Flag	Coverage Δ
e2e	35.62% <0.00%> (-0.29%)	⬇️
integration	56.41% <0.00%> (-0.46%)	⬇️
unit	79.94% <77.27%> (+1.19%)	⬆️

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[vdusek]

Consolidated into #979, which now carries these lifecycle fixes on top of the startup-race fix. Closing in favor of #979.