ANL worker: converting to flatland is not the same as creating a farm

Farms have a multi turn cycle:
1) crate farm (converts to Re)
2) end turn on the filed to harvest (Re has been automatically converted)
3) convert to grasland [othrwise the fields remains unusable for building]

Step 3 was labeled the same as step 1.

[ci skip]

(cherry-picked from commit 1867274)

data/multiplayer/scenarios/ANL_utils/ANL_worker_options.cfg

@@ -60,7 +60,7 @@
 
                         [option]
                             image = "terrain/grass/green6.png"
-                            label= "<span color='green'>" + _ "Plant Farm" + "</span>"
+                            label= "<span color='green'>" + _ "Convert to grassland" + "</span>"
                             description = "<span size='small'>" + _ "Cost: 0g" + "</span>"
                             {ANL_SHOW_IF ("Peasant") "Re"}
                             [command]
@@ -78,7 +78,7 @@
                         # Plant Farm
 
                         [option]
-                            image = "terrain/grass/green6.png"
+                            image = "terrain/embellishments/farm-veg-spring-icon.png"
                             label = "<span color='green'>" + _ "Plant Farm" + "</span>"
                             description = "<span size='small'>" + _ "Cost: 0g" + "</span>"
                             {ANL_SHOW_IF ("Peasant") "Gg,Gs"}