Improve PHPStan config #1375

Job	Run time
static-analysis (8.3, cs)	24s
static-analysis (8.3, stan)	42s
static-analysis (8.3, swagger:validate)	14s
api-tests / tests (8.2)	1m 21s
cli-tests / tests (8.2)	35s
api-tests / tests (8.3)	1m 15s
unit-tests / tests (8.2)	19s
cli-tests / tests (8.3)	38s
api-tests / tests (8.4)	1m 35s
unit-tests / tests (8.3)	19s
cli-tests / tests (8.4)	35s
unit-tests / tests (8.4)	19s
db-tests (maria) / db-tests (8.2)	55s
db-tests (maria) / db-tests (8.3)	23s
db-tests (maria) / db-tests (8.4)	33s
db-tests (mysql) / db-tests (8.2)	44s
db-tests (ms) / db-tests (8.2)	56s
db-tests (postgres) / db-tests (8.2)	35s
db-tests (mysql) / db-tests (8.3)	31s
db-tests (ms) / db-tests (8.3)	44s
db-tests (postgres) / db-tests (8.3)	22s
db-tests (mysql) / db-tests (8.4)	40s
db-tests (sqlite:ci) / db-tests (8.2)	19s
db-tests (ms) / db-tests (8.4)	50s
db-tests (postgres) / db-tests (8.4)	35s
db-tests (sqlite:ci) / db-tests (8.3)	26s
db-tests (sqlite:ci) / db-tests (8.4)	21s
upload-coverage (8.3)	24s
delete-artifacts	2s
	17m 36s

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