fix: down migrations in newer MySQL versions #2750

Job	Run time
Run tests and lints	7m 40s
Run HSM tests	7m 5s
Run end-to-end tests (cockroach, --jwt)	6m 34s
Run end-to-end tests (cockroach)	6m 36s
Run end-to-end tests (mysql, --jwt)	6m 1s
Run end-to-end tests (mysql)	5m 49s
Run end-to-end tests (postgres)	5m 21s
Run end-to-end tests (postgres, --jwt)	5m 22s
Run end-to-end tests (memory)	5m 23s
Run end-to-end tests (memory, --jwt)	5m 38s
Run OIDC conformity tests	8m 42s
Build CLI docs	1m 18s
Generate release	-1s
Draft newsletter	-1s
Send newsletter	0s
Pending approval Slack notification	0s
	1h 11m 27s

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