prepare-root: Drop redundant print about signature/digest

We print if we're doing a signature+digest verification; its absence is
sufficient in the other case.  The goal here is to avoid polluting
the logs when signatures are not enabled.

src/switchroot/ostree-prepare-root.c

@@ -493,7 +493,6 @@ main (int argc, char *argv[])
           // Or stated in reverse: if signature verification is enabled, then digest verification
           // must also be.
           g_assert (!composefs_config->is_signed);
-          g_print ("composefs: Mounting with no digest or signature check\n");
         }
 
       if (lcfs_mount_image (OSTREE_COMPOSEFS_NAME, TMP_SYSROOT, &cfs_options) == 0)