roachprod: change scp flags to avoid copy via local host

Previously default scp option made it to copy files via local host.
This was causing unnecessary delays and network usage because files
were first copied to one node, then distributed from that node using
scp between remote locations. Unfortunately the default scp behaviour
is to fetch from src and put to dst to avoid authenticating from src
to dst.
This commit adds scp options to do direct copy.

Fixes: #99103

Release note: None

pkg/roachprod/install/cluster_synced.go

@@ -2381,7 +2381,9 @@ func (c *SyncedCluster) SSH(ctx context.Context, l *logger.Logger, sshArgs, args
 // which we do want to be able to retry.
 func scp(src, dest string) (*RunResultDetails, error) {
 	args := []string{
-		"scp", "-r", "-C",
+		"scp",
+		// ssh to src then scp dsc mode, use agent forwarding, recursive, compression
+		"-R", "-A", "-r", "-C",
 		"-o", "StrictHostKeyChecking=no",
 	}
 	args = append(args, sshAuthArgs()...)