feat: add ceph df to ceph collector #3763

Job	Run time
test	6m 0s
ensure-schemas-are-generated	4m 41s
test-integration	4m 26s
compile-collect	3m 21s
compile-preflight	3m 47s
compile-supportbundle	3m 45s
fail_if_pull_request_is_draft	0s
goreleaser-test (amd64, darwin)	2m 45s
run-examples	1m 17s
goreleaser-test (amd64, linux)	3m 14s
goreleaser-test (amd64, windows)	2m 53s
goreleaser-test (arm64, darwin)	32s
goreleaser-test (arm64, linux)	3m 0s
goreleaser-test (arm64, windows)	31s
goreleaser-test (arm, linux)	3m 6s
validate-supportbundle-e2e-go-test	4m 59s
validate-supportbundle	3m 10s
validate-supportbundle-e2e	1m 3s
validate-preflight-e2e	1m 6s
validate-preflight	34s
goreleaser	0s
	54m 10s

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