[multiverse RPC]: add better universe root node cache #3431

Job	Run time
Format check	29s
Compilation check	43s
cross compilation	4m 49s
Docker build check	3m 43s
run itests	8m 41s
run itests postgres	17m 16s
Lint check	2m 46s
migration version check	11s
RPC check	1m 15s
go mod check	1m 8s
run LiT tests	13m 24s
sample configuration check	37s
Sqlc check	1m 0s
test vector check	50s
run unit tests (unit-race)	9m 31s
run unit tests (unit-cover)	3m 3s
run unit tests (unit dbbackend=postgres)	5m 43s
finish	5s
	1h 15m 14s

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