fix: remove trailing slash from metrics server endpoint (#401)

[vitaliy-guliy]

What does this PR do?

Cherry-pick of #401

What issues does this PR fix?

eclipse-che/che#23044
eclipse-che/che#23066

How to test this PR?

See #401

Does this PR contain changes that override default upstream Code-OSS behavior?

• the PR contains changes in the code folder (you can skip it if your changes are placed in a che extension )
• the corresponding items were added to the CHANGELOG.md file
• rules for automatic git rebase were added to the .rebase folder

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Pull Request images published ✨

Editor: quay.io/che-incubator-pull-requests/che-code:pr-408-amd64
Dev image: quay.io/che-incubator-pull-requests/che-code-dev:pr-408-dev-amd64

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Build 3.16 :: code_3.16/6: Console, Changes, Git Data

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Build 3.16 :: sync-to-downstream_3.16/101: Console, Changes, Git Data

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Build 3.16 :: get-sources-rhpkg-container-build_3.16/98: Console, Changes, Git Data

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Build 3.16 :: get-sources-rhpkg-container-build_3.16/98:

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