virsh: qemu-monitor-command: Don't print extra newline with --pretty

The prettified JSON string already contains a newline so don't print
another one. This allows to pipe the json output (in conjunction with
the --quiet option) to files without having to truncate them afterwards.

tools/virsh-domain.c

@@ -8972,6 +8972,7 @@ cmdQemuMonitorCommand(vshControl *ctl, const vshCmd *cmd)
         if (pretty && (tmp = virJSONValueToString(pretty, true))) {
             VIR_FREE(result);
             result = tmp;
+            virTrimSpaces(result, NULL);
         } else {
             vshResetLibvirtError();
         }