multi: add new build tag integration

This commit adds a new build tag `integration` and removes the old tag
`rpctest` for clarity. Multiple unnecessary usages of `build !rpctest`
is also removed.

aezeed/cipherseed_integration.go

@@ -1,5 +1,4 @@
-//go:build rpctest
-// +build rpctest
+//go:build integration
 
 package aezeed