Fix Observable.take scheduler annotation

[evgenyponomarev]

Summary

• change the scheduler support for Observable.take(long, TimeUnit) from NONE to COMPUTATION
• align the annotation with the default timer(time, unit) implementation, its Javadoc, and the equivalent Flowable overload

Fixes #8288

Validation

• ./gradlew test --tests "io.reactivex.rxjava4.validators.CheckBaseTypeAnnotationsTest" --tests "io.reactivex.rxjava4.validators.CheckJavadocForAnnotationsTest"
• ./gradlew test --tests "io.reactivex.rxjava4.validators.*" --stacktrace --no-daemon
• ./gradlew build --stacktrace
• ./gradlew javadoc --stacktrace

AI disclosure

This contribution was made with OpenAI Codex assistance. Codex inspected the current 4.x implementation and contribution policy, applied the one-line annotation correction, and ran the validation listed above. The reasoning was that this overload delegates to the default computation-scheduler timer, its Javadoc already documents computation scheduling, and the equivalent Flowable overload already uses SchedulerSupport.COMPUTATION.

[github-actions]

🐷 TruffleHog + Entropy Beauty Scan

Average entropy of changed code: 4.763 bits/char
Verdict: ⚠️ Consider review — entropy outside sweet spot

Changed files entropy:

src/main/java/io/reactivex/rxjava4/core/Observable.java: 4.763

✅ 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 98.61%. Comparing base (4e481d5) to head (3f0e302).

Additional details and impacted files

@@            Coverage Diff            @@
##                4.x    #8289   +/-   ##
=========================================
  Coverage     98.60%   98.61%           
+ Complexity     7150     7149    -1     
=========================================
  Files           824      824           
  Lines         50791    50791           
  Branches       6911     6911           
=========================================
+ Hits          50084    50088    +4     
+ Misses          482      480    -2     
+ Partials        225      223    -2     

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