refactor: cleanup `DatabaseHandler::gc()` for session #12363

Job	Run time
Setup PHP Version for Code Coverage	1s
Others (8.2) / Sanity Tests	3m 33s
Others (8.1) / Sanity Tests	2m 20s
Others (8.3) / Sanity Tests	2m 39s
CacheLive (8.2) / Cache Live Tests	2m 7s
DatabaseLive (8.1, MySQLi, 5.7) / tests	2m 48s
CacheLive (8.3) / Cache Live Tests	2m 46s
CacheLive (8.1) / Cache Live Tests	2m 9s
DatabaseLive (8.1, MySQLi, 8.0) / tests	4m 30s
DatabaseLive (8.1, OCI8, 8.0) / tests	6m 9s
DatabaseLive (8.1, Postgre, 8.0) / tests	2m 27s
DatabaseLive (8.1, SQLite3, 8.0) / tests	2m 24s
DatabaseLive (8.1, SQLSRV, 8.0) / tests	3m 58s
DatabaseLive (8.2, MySQLi, 8.0) / tests	4m 41s
DatabaseLive (8.2, OCI8, 8.0) / tests	6m 57s
DatabaseLive (8.2, Postgre, 8.0) / tests	3m 30s
DatabaseLive (8.2, SQLite3, 8.0) / tests	3m 43s
DatabaseLive (8.2, SQLSRV, 8.0) / tests	4m 38s
DatabaseLive (8.3, MySQLi, 8.0) / tests	4m 30s
DatabaseLive (8.3, OCI8, 8.0) / tests	6m 1s
DatabaseLive (8.3, Postgre, 8.0) / tests	2m 41s
DatabaseLive (8.3, SQLite3, 8.0) / tests	2m 29s
DatabaseLive (8.3, SQLSRV, 8.0) / tests	4m 18s
SeparateProcess (8.1) / tests	3m 31s
SeparateProcess (8.3) / tests	3m 14s
SeparateProcess (8.2) / tests	3m 23s
Upload coverage results to Coveralls / coveralls	38s
	1h 32m 5s

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