ci: remove gitlab ci docs job #15

Job	Run time
ci-amd64 / check-docker-artifact-existence	1s
ci-amd64 / check-dockerfile-modifications-with-last-commit	3s
ci-amd64 / check-dockerfile-modifications-with-base	3s
ci-amd64 / build-image	0s
ci-amd64 / compile-and-test-standard	4m 0s
ci-amd64 / compile-and-test-local-custom-image	0s
ci-amd64 / analyze-coverage-report	15s
	4m 22s

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