roachprod: only wait on boot disk

Previously, during the wait for VMs to start we would check both the boot disk
and the data disk. But in order to support VMs that only have a boot disk we
should not be checking the data disk here. This change updates `Wait` to only
check the boot disk.

Epic: None
Release note: None

Author: herkolategan

pkg/roachprod/install/cluster_synced.go

@@ -1085,7 +1085,10 @@ func (c *SyncedCluster) Wait(ctx context.Context, l *logger.Logger) error {
 		func(ctx context.Context, node Node) (*RunResultDetails, error) {
 			res := &RunResultDetails{Node: node}
 			var err error
-			cmd := fmt.Sprintf("test -e %s -a -e %s", vm.DisksInitializedFile, vm.OSInitializedFile)
+			// Only the `vm.OSInitializedFile` file is checked and not the
+			// `vm.DisksInitializedFile`, because it's possible to create VMs without
+			// any attached disks other than the boot disk.
+			cmd := fmt.Sprintf("test -e %s", vm.OSInitializedFile)
 			// N.B. we disable ssh debug output capture, lest we end up with _thousands_ of useless .log files.
 			opts := cmdOptsWithDebugDisabled()
 			for j := 0; j < 600; j++ {