Remove directory from /doc-locale of redirectes

What does this MR do and why?

Currently, these are the terminal errors found after these changes are made to hugo.yml and running make view.

ERROR [ja-jp] REF_NOT_FOUND: Ref "../code_coverage/_index" from page "/ci/testing/test_coverage_visualization": page not found
WARN Invalid internal redirect path in _index: ../code_coverage/_index.md
ERROR [ja-jp] REF_NOT_FOUND: Ref "../code_coverage/cobertura" from page "/ci/testing/test_coverage_visualization/cobertura": page not found
WARN Invalid internal redirect path in cobertura: ../code_coverage/cobertura.md
ERROR [ja-jp] REF_NOT_FOUND: Ref "../code_coverage/jacoco" from page "/ci/testing/test_coverage_visualization/jacoco": page not found
WARN Invalid internal redirect path in jacoco: ../code_coverage/jacoco.md
Built in 2711 ms
Error: error building site: logged 3 error(s)
make: *** [view] Error 1

Removes these redirect files from /doc-locale makes the build successful with i18n enabling Hugo for docs.gitlab.com/ja-jp/.

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

Since these files are not used yet in our docs project, there isn't a good way to test this change.

You could follow the steps here to set up our main-development environment from our localization forks: https://handbook.gitlab.com/handbook/marketing/localization/engineering/#i18n-development-environments

MR acceptance checklist

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