chore: fix typos in CompactionService #4474

Job	Run time
end2end_test_prep	1m 13s
functional_tests (stable)	2m 8s
functional_tests (beta)	1m 59s
unit_tests (stable)	3m 5s
unit_tests (beta)	3m 6s
end2end_test_staging	3m 29s
end2end_test_12	2m 5s
end2end_test_34	2m 5s
end2end_test_56	2m 0s
push_canary_secondary_image	0s
push_prod_secondary_image	0s
push_prod_virtualenv_image	0s
push_canary_virtualenv_image	0s
push_staging_observable_secondary_image	0s
push_staging_virtual_env_images	0s
push_staging_secondary_image	0s
	21m 10s

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