tests: replace QTest::qWait(N) with signal-based waits

Fixed-time sleeps are a source of intermittent failures on slow CI
machines — if the delay is too short, the test races ahead of the
code under test.

Replacements made:
- dolphinmainwindowtest: qWait() calls replaced with QTRY_COMPARE,
  QTRY_VERIFY, qWaitFor lambdas and processEvents() where animations
  are disabled; one genuinely unavoidable timer wait marked
  // UNAVOIDABLE:
- kitemlistcontrollerexpandtest: qWaitFor(..., 100ms) / qWaitFor(...,
  300ms) replaced with spy->wait() loops that block until all
  expected directoryLoadingCompleted signals have arrived
- kitemlistkeyboardsearchmanagertest: timer-driven wait marked
  // UNAVOIDABLE: (must wait for keyboard search timeout to expire)

Add testhelpers.h providing TestHelpers::disableAnimations(), which
eliminates the need for delays that previously waited for Qt UI
animations to settle.

0 files changed, 0 insertions, 0 deletions