op-mode: T6971: "monitor log" should have no output color at all

There was an invalid attempt to remove journalctl output colour. Unfortunately
it does not work 100% and it needs a different environment variable.

This fixes commit 9a85d8b.

Author: c-po

op-mode-definitions/monitor-log.xml.in

@@ -9,13 +9,13 @@
         <properties>
           <help>Monitor last lines of messages file</help>
         </properties>
-        <command>SYSTEMD_LOG_COLOR=false journalctl --no-hostname --follow --boot</command>
+        <command>SYSTEMD_COLORS=false journalctl --no-hostname --follow --boot</command>
         <children>
           <node name="color">
             <properties>
               <help>Output log in a colored fashion</help>
             </properties>
-            <command>SYSTEMD_LOG_COLOR=false grc journalctl --no-hostname --follow --boot</command>
+            <command>SYSTEMD_COLORS=false grc journalctl --no-hostname --follow --boot</command>
           </node>
           <node name="ids">
             <properties>