refactor: cleanup `DatabaseHandler::gc()` for session #12358

Job	Run time
Setup PHP Version for Code Coverage	1s
Others (8.1) / Sanity Tests	2m 52s
Others (8.2) / Sanity Tests	4m 3s
Others (8.3) / Sanity Tests	2m 56s
SeparateProcess (8.1) / tests	3m 38s
SeparateProcess (8.2) / tests	3m 33s
SeparateProcess (8.3) / tests	3m 21s
DatabaseLive (8.1, MySQLi, 5.7) / tests	3m 0s
DatabaseLive (8.1, MySQLi, 8.0) / tests	4m 5s
DatabaseLive (8.1, OCI8, 8.0) / tests	6m 3s
DatabaseLive (8.1, Postgre, 8.0) / tests	2m 52s
DatabaseLive (8.1, SQLite3, 8.0) / tests	2m 32s
DatabaseLive (8.1, SQLSRV, 8.0) / tests	4m 17s
DatabaseLive (8.2, MySQLi, 8.0) / tests	4m 55s
CacheLive (8.1) / Cache Live Tests	2m 9s
CacheLive (8.3) / Cache Live Tests	2m 8s
CacheLive (8.2) / Cache Live Tests	2m 19s
DatabaseLive (8.2, OCI8, 8.0) / tests	6m 59s
DatabaseLive (8.2, Postgre, 8.0) / tests	3m 25s
DatabaseLive (8.2, SQLite3, 8.0) / tests	3m 28s
DatabaseLive (8.2, SQLSRV, 8.0) / tests	4m 48s
DatabaseLive (8.3, MySQLi, 8.0) / tests	4m 27s
DatabaseLive (8.3, OCI8, 8.0) / tests	5m 51s
DatabaseLive (8.3, Postgre, 8.0) / tests	3m 16s
DatabaseLive (8.3, SQLite3, 8.0) / tests	2m 47s
DatabaseLive (8.3, SQLSRV, 8.0) / tests	4m 39s
Upload coverage results to Coveralls / coveralls	47s
	1h 35m 11s

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