fix(gc): skip deleted miner actors in StorageGCMark #2367

Job	Run time
ci-lint	22s
build-forest	5m 29s
build-supraseal-ubuntu24	5m 32s
setup-params	10s
gofmt	29s
build-calibnet	5m 34s
build-mainnet	5m 22s
gen-check	7m 3s
build-2k	5m 18s
mod-tidy-check	1m 3s
lint	4m 22s
build-debug	5m 28s
test (test-itest-harmonyDB, ./itests/harmonydb_test.go)	2m 30s
test (test-all, `go list ./... \| grep -v curio/itests`)	6m 5s
test (test-itest-pdp-prove, ./itests/pdp_prove_test.go)	1m 38s
test (test-itest-curio, ./itests/curio_test.go)	5m 14s
test (test-itest-alertnow, ./itests/alertnow_test.go)	2m 40s
coverage-report	45s
required-checks-passed	3s
	1h 5m 7s

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