[8.4](backport #1870) Make authc log debug and add cache hit field

[mergify]

This is an automatic backport of pull request #1870 done by Mergify.
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On branch mergify/bp/8.4/pr-1870
Your branch is up to date with 'origin/8.4'.

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Changes to be committed:
	modified:   internal/pkg/api/auth.go

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	both modified:   CHANGELOG.next.asciidoc

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• Start Time: 2022-09-19T11:17:43.962+0000

• Duration: 10 min 6 sec

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Total	305

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[mergify]

This pull request has not been merged yet. Could you please review and merge it @joshdover? 🙏