Fix registration of RocksDB metrics categories

[fab-10]

PR description

Fix a regression in the registration of RocksDB metrics categories introduced by #7825

Fixed Issue(s)

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• Checked out our contribution guidelines?
• Considered documentation and added the doc-change-required label to this PR if updates are required.
• Considered the changelog and included an update if required.
• For database changes (e.g. KeyValueSegmentIdentifier) considered compatibility and performed forwards and backwards compatibility tests

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• unit tests: ./gradlew build
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• integration tests: ./gradlew integrationTest
• reference tests: ./gradlew ethereum:referenceTests:referenceTests

[Gabriel-Trintinalia]

lgtm