Fix flaky test ContextCancellationTest

[jrhee17]

Motivation:

Let me just remove the validation like @minwoox suggested

Modifications:

• Removed the validation on request context.

Result:

• Test failure: com.linecorp.armeria.client.ContextCancellationTest.cancel_beforeWriteFinished(TestInfo) #5868

[ikhoon]

The CI status is unstable. I will postpone the release process until this issue is fixed.
https://github.com/line/armeria/actions/runs/10348301653/job/28640280474#step:11:1945
https://github.com/line/armeria/actions/runs/10348301653/job/28640279386#step:11:2068

[jrhee17]

The CI status is unstable. I will postpone the release process until this issue is fixed.

Sorry about this, will fix ASAP

[ikhoon]

No worries. Take your time. 😉

[jrhee17]

Ready for review

[github-actions]

🔍 Build Scan® (commit: 746fa93)

Job name	Status	Build Scan®
build-self-hosted-unsafe-jdk-8	✅	https://ge.armeria.dev/s/gi5ottmxp62iw
build-self-hosted-unsafe-jdk-21-snapshot-blockhound	✅	https://ge.armeria.dev/s/m6dmmwzhpsegi
build-self-hosted-unsafe-jdk-17-min-java-17-coverage	✅	https://ge.armeria.dev/s/sguig4exvwyco
build-self-hosted-unsafe-jdk-17-min-java-11	✅	https://ge.armeria.dev/s/4dxuxtrx73ao2
build-self-hosted-unsafe-jdk-17-leak	✅	https://ge.armeria.dev/s/xjio47gjp5cy6
build-self-hosted-unsafe-jdk-11	✅	https://ge.armeria.dev/s/l7h57d55l2mec
build-macos-12-jdk-21	✅	https://ge.armeria.dev/s/6es2tigsgk3aw

[minwoox]

👍 👍 👍

[ikhoon]

🙇‍♂️🙇‍♂️