4.x: Cleanup, wording minor things

[akarnokd]

• Decided to use Cancelled with two Ls because API already usees that spelling.
• signalled -> signaled
• Timed is now a record class.

[github-actions]

🐷 TruffleHog + Entropy Beauty Scan

Average entropy of changed code: 4.636 bits/char
Verdict: ✅ Mid-4 beauty detected (thoughtful human code!)

Changed files entropy:

build.gradle: 5.005
src/main/java/io/reactivex/rxjava4/disposables/Disposable.java: 4.677
src/main/java/io/reactivex/rxjava4/disposables/DisposableContainer.java: 4.421
src/main/java/io/reactivex/rxjava4/internal/operators/flowable/FlowableRefCount.java: 4.338
src/main/java/io/reactivex/rxjava4/internal/operators/observable/ObservableAmb.java: 4.224
src/main/java/io/reactivex/rxjava4/internal/operators/observable/ObservableCombineLatest.java: 4.104
src/main/java/io/reactivex/rxjava4/internal/operators/observable/ObservableRefCount.java: 4.318
src/main/java/io/reactivex/rxjava4/internal/operators/observable/ObservableZip.java: 3.973
src/main/java/io/reactivex/rxjava4/internal/schedulers/DeferredExecutorScheduler.java: 3.992
src/main/java/io/reactivex/rxjava4/internal/schedulers/ExecutorScheduler.java: 4.073
src/main/java/io/reactivex/rxjava4/internal/util/AwaitCoordinatorStatic.java: 4.508
src/main/java/io/reactivex/rxjava4/internal/virtual/FlowableVirtualCreateExecutor.java: 4.454
src/main/java/io/reactivex/rxjava4/internal/virtual/FlowableVirtualTransformExecutor.java: 4.143
src/test/java/io/reactivex/rxjava4/completable/CompletableTest.java: 4.630
src/test/java/io/reactivex/rxjava4/core/DisposeTaskTest.java: 4.772
src/test/java/io/reactivex/rxjava4/core/PeriodicDirectTaskTest.java: 4.776
src/test/java/io/reactivex/rxjava4/disposables/CompositeDisposableTest.java: 4.490
src/test/java/io/reactivex/rxjava4/disposables/DisposableTest.java: 4.643
src/test/java/io/reactivex/rxjava4/disposables/FutureDisposableTest.java: 4.892
src/test/java/io/reactivex/rxjava4/disposables/SerialDisposableTests.java: 4.541

✅ No secrets or suspicious high-entropy strings found.

Mid-4 beauty heuristic in action — powered by our entropy chats! 😊

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.34%. Comparing base (78230e3) to head (fdb5226).

Additional details and impacted files

@@             Coverage Diff              @@
##                4.x    #8186      +/-   ##
============================================
+ Coverage     98.32%   98.34%   +0.01%     
+ Complexity     6936     6928       -8     
============================================
  Files           785      785              
  Lines         48998    48981      -17     
  Branches       6599     6595       -4     
============================================
- Hits          48179    48170       -9     
+ Misses          622      615       -7     
+ Partials        197      196       -1     

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