node/grpc: Return to passthrough address resolution scheme

979811e switched SN-to-SN gRPC dial
approach from 'passthrough' resolution scheme (used by `grpc.Dial*`
functions) to the `dns` one (`grpc.NewClient`). This was not
intentional, but it did cause visible changes in behavior. The DNS
resolver began to introduce time costs into processing. This became
especially noticeable on the test macOS env, where delays reached 10s
causing tests to fall on deadline. On Linux, delays also increased, but
by negligible amounts.

This returns SN to using global 'passthrough' resolver.

Fixes #3250.

Signed-off-by: Leonard Lyubich <[email protected]>

Author: cthulhu-rider

cmd/neofs-node/grpc.go

@@ -14,9 +14,13 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/keepalive"
+	"google.golang.org/grpc/resolver"
 )
 
 func initGRPC(c *cfg) {
+	// although docs state that 'passthrough' is set by default, it should be set explicitly for activation
+	resolver.SetDefaultScheme("passthrough")
+
 	if c.cfgMorph.client == nil {
 		initMorphComponents(c)
 	}