Respect user-provided `serviceLevelObjectives` in timer histogram metrics

[ks-yim]

Motivation:

Armeria allows overriding its default distribution metric config but servieLevelObjectives config is not respected in its timer metrics

Modification:

Made Armeria respect user-provided serviceLevelObjectives in its timer histogram metrics.

Result:

• Timer histogram metrics exposed by Armeria repects user-provided serviceLevelObjectives.

[CLAassistant]

All committers have signed the CLA.

[github-actions[bot]]

🔍 Build Scan® (commit: 569e11044319915559cd11806348ef24d656711a)

Job name	Status	Build Scan®
build-windows-latest-jdk-19	✅	https://ge.armeria.dev/s/2sm45qdh5vzfm
build-self-hosted-unsafe-jdk-8	✅	https://ge.armeria.dev/s/wfnrrmzlexniy
build-self-hosted-unsafe-jdk-19-snapshot-blockhound	✅	https://ge.armeria.dev/s/pd2mvvx2nfnw6
build-self-hosted-unsafe-jdk-17-min-java-17-coverage	✅	https://ge.armeria.dev/s/vnz46yh2rmdpm
build-self-hosted-unsafe-jdk-17-min-java-11	✅	https://ge.armeria.dev/s/lqcpzjzthvw6q
build-self-hosted-unsafe-jdk-17-leak	✅	https://ge.armeria.dev/s/7dhsbcv4usdls
build-self-hosted-unsafe-jdk-11	✅	https://ge.armeria.dev/s/chvnqzygtyf22
build-macos-12-jdk-19	✅	https://ge.armeria.dev/s/venrwxvsfauxa