multi: fix `staticcheck` flags #2805

Job	Run time
run unit-test postgres race	10m 28s
verify that auto-generated documentation is up-to-date	26s
go mod check	10m 24s
RPC compilation check	1m 30s
SQL compilation check	8s
build and lint code	4m 52s
run LiT unit tests	6m 17s
run unit-test sqlite3 race	8m 41s
run LiT itests	5m 29s
	48m 15s

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