test: mark test_breakpad_dump_inflight as flaky with timeout

[jpnurmi]

Add a 5-minute timeout, which should be generous enough even for busy CI environments, and retry up to 3 times to prevent the test from hanging indefinitely, or 6 hours in CI.

Close: #1501

[jpnurmi]

Example:

===Flaky Test Report===
test_breakpad_dump_inflight failed (2 runs remaining out of 3).
	<class 'subprocess.TimeoutExpired'>
	Command '['C:\\Users\\runneradmin\\AppData\\Local\\Temp\\pytest-of-runneradmin\\pytest-0\\cmake26\\sentry_example.exe', 'log', 'capture-multiple', 'crash']' timed out after 300.0 seconds
	[<TracebackEntry C:\hostedtoolcache\windows\Python\3.12.10\x64\Lib\site-packages\_pytest\runner.py:340>, <TracebackEntry C:\hostedtoolcache\windows\Python\3.12.10\x64\Lib\site-packages\flaky\flaky_pytest_plugin.py:146>, <TracebackEntry C:\hostedtoolcache\windows\Python\3.12.10\x64\Lib\site-packages\pluggy\_hooks.py:512>, <TracebackEntry C:\hostedtoolcache\windows\Python\3.12.10\x64\Lib\site-packages\pluggy\_manager.py:120>, <TracebackEntry C:\hostedtoolcache\windows\Python\3.12.10\x64\Lib\site-packages\pluggy\_callers.py:167>, <TracebackEntry C:\hostedtoolcache\windows\Python\3.12.10\x64\Lib\site-packages\pluggy\_callers.py:139>, <TracebackEntry C:\hostedtoolcache\windows\Python\3.12.10\x64\Lib\site-packages\_pytest\threadexception.py:87>, <TracebackEntry C:\hostedtoolcache\windows\Python\3.12.10\x64\Lib\site-packages\_pytest\threadexception.py:63>, <TracebackEntry C:\hostedtoolcache\windows\Python\3.12.10\x64\Lib\site-packages\pluggy\_callers.py:139>, <TracebackEntry C:\hostedtoolcache\windows\Python\3.12.1
test_breakpad_dump_inflight passed 1 out of the required 1 times. Success!
test_shutdown_timeout passed 1 out of the required 1 times. Success!
===End Flaky Test Report===
================ 903 passed, 22 skipped in 1681.44s (0:28:01) =================

[JoshuaMoelans]

lgtm, thanks!