Fix 11 flaky tests in camel-core caused by timing issues

[gnodet]

Summary

Fix 11 intermittently failing tests in camel-core that pass on rerun (rerunFailingTestsCount=2), confirming they are timing-dependent.

File consumer delay=10 re-read fixes (6 tests)

File consumer with delay=10 (10ms poll interval) re-reads files before they are moved to .camel/, creating duplicate exchanges. Increased to delay=2000 for a single poll per test lifetime.

• FileSedaShutdownCompleteAllTasksTest (expected 5, got 9)
• ShutdownCompleteCurrentTaskOnlyTest (expected <5, got 5)
• MarkerFileExclusiveReadLockStrategyTest
• MarkerFileExclusiveReadLockStrategyUnlockTest
• MarkerFileExclusiveReadLockStrategyRecursiveCleanupTest (5 test methods)
• FileConsumeFilesAndDeleteTest

Thread pool / timing fixes (4 tests)

• MulticastParallelStreamingTimeoutTest (expected "CB", got "Hello"): Thread pool starvation under CI prevented branches from completing within 5s timeout. Increased multicast timeout to 10s, direct:a delay to 20s.
• MulticastParallelStreamingTest (expected "BA", got "AB"): asyncDelayed() uses scheduled executor subject to thread pool pressure. Switched to syncDelayed() (Thread.sleep) for deterministic ordering.
• RecipientListParallelStreamingTest: Same asyncDelayed() issue. Added syncDelayed().
• MulticastParallelTimeoutStreamCachingTest (expected mock:exception=1, got 0): IOException propagation exceeded default mock assertion timeout. Added explicit setResultWaitTime(15000).

Aggregation timeout fix (1 test)

• AggregateCompleteAllOnStopTest: completionTimeout(100ms) fires between messages under CI load, prematurely completing aggregations. Increased to 5000ms.

Test plan

• All 11 tests pass locally (21 test methods, 0 failures)
• CI passes

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🧪 CI tested the following changed modules:

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