Chore: clean old CI versions & exceptions #2580

Job	Run time
CI (20.x, postgres)	59s
Test user experience (20.x, ubuntu-latest)	26s
CI (20.x, pgnative)	1m 12s
Test user experience (20.x, macos-latest)	44s
CI (20.x, mysql)	1m 9s
Test user experience (20.x, windows-latest)	9m 49s
CI (20.x, mssql)	1m 21s
CI (20.x, sqlite3)	43s
CI (20.x, cockroachdb)	1m 58s
CI (20.x, better-sqlite3)	45s
CI (20.x, oracledb)	6m 26s
CI (18.x, postgres)	1m 4s
CI (18.x, pgnative)	1m 21s
CI (18.x, mysql)	1m 13s
CI (18.x, mssql)	1m 25s
CI (18.x, sqlite3)	43s
CI (18.x, cockroachdb)	1m 56s
CI (18.x, better-sqlite3)	43s
CI (18.x, oracledb)	5m 17s
CI (16.x, postgres)	2m 9s
CI (16.x, pgnative)	2m 2s
CI (16.x, mysql)	2m 17s
CI (16.x, mssql)	1m 57s
CI (16.x, sqlite3)	1m 45s
CI (16.x, cockroachdb)	2m 54s
CI (16.x, better-sqlite3)	1m 47s
CI (16.x, oracledb)	7m 17s
	1h 1m 22s

Provide feedback