docs: fix/add @return types in DB Connection #11505

Job	Run time
Setup PHP Version for Code Coverage	1s
Others (8.1) / Sanity Tests	3m 7s
Others (8.2) / Sanity Tests	27m 54s
Others (8.3) / Sanity Tests	2m 52s
CacheLive (8.2) / Cache Live Tests	3m 30s
CacheLive (8.1) / Cache Live Tests	2m 20s
CacheLive (8.3) / Cache Live Tests	2m 25s
DatabaseLive (8.1, MySQLi, 5.7) / tests	11m 45s
DatabaseLive (8.1, OCI8, 8.0) / tests	6m 32s
DatabaseLive (8.1, Postgre, 8.0) / tests	2m 58s
DatabaseLive (8.1, MySQLi, 8.0) / tests	5m 57s
DatabaseLive (8.1, SQLite3, 8.0) / tests	1h 10m 13s
DatabaseLive (8.1, SQLSRV, 8.0) / tests	5m 8s
DatabaseLive (8.2, MySQLi, 8.0) / tests	4m 56s
DatabaseLive (8.2, OCI8, 8.0) / tests	7m 42s
DatabaseLive (8.2, Postgre, 8.0) / tests	4m 7s
DatabaseLive (8.2, SQLite3, 8.0) / tests	3m 34s
DatabaseLive (8.2, SQLSRV, 8.0) / tests	5m 38s
DatabaseLive (8.3, MySQLi, 8.0) / tests	6m 3s
DatabaseLive (8.3, OCI8, 8.0) / tests	5m 59s
DatabaseLive (8.3, Postgre, 8.0) / tests	3m 26s
DatabaseLive (8.3, SQLite3, 8.0) / tests	51m 22s
DatabaseLive (8.3, SQLSRV, 8.0) / tests	53m 42s
SeparateProcess (8.1) / tests	3m 28s
SeparateProcess (8.2) / tests	3m 33s
SeparateProcess (8.3) / tests	4m 8s
Upload coverage results to Coveralls / coveralls	36s
	5h 2m 56s

Provide feedback