ENG-48179: Revert NewClient api usage in configgrpc.

With NewClient API usage, we are facing issues at few customers
who have intermediate proxies between collector and platform.
With NewClient API instead DialContext, DNS resolution happens
on the client side while it should happen on proxy.
Also, with SGProxy client does not get the correct certificate.
can be changed once grpc fixes grpc/grpc-go#7556
and otel collector picks the fix

config/configgrpc/configgrpc.go

@@ -224,7 +224,7 @@ func (gcs *ClientConfig) ToClientConn(ctx context.Context, host component.Host,
 		return nil, err
 	}
 	opts = append(opts, extraOpts...)
-	return grpc.NewClient(gcs.sanitizedEndpoint(), opts...)
+	return grpc.DialContext(ctx, gcs.sanitizedEndpoint(), opts...)
 }
 
 func (gcs *ClientConfig) toDialOptions(ctx context.Context, host component.Host, settings component.TelemetrySettings) ([]grpc.DialOption, error) {