Revert Tertiary button to its previous style

The styling of the Tertiary button (to not look like a link anymore) and the introduction of the Quatertiary button (as the link button) will happen in a separate ticket in the future.

CURA-8012

resources/qml/TertiaryButton.qml

@@ -12,8 +12,8 @@ Cura.ActionButton
     color: "transparent"
     textColor: UM.Theme.getColor("text_link")
     outlineColor: "transparent"
-    outlineDisabledColor: "transparent"
-    disabledColor: "transparent"
+    disabledColor: UM.Theme.getColor("action_button_disabled")
     textDisabledColor: UM.Theme.getColor("action_button_disabled_text")
-    hoverColor: UM.Theme.getColor("tertiary_button_hover")
-}
+    hoverColor: "transparent"
+    underlineTextOnHover: true
+}

resources/themes/cura-dark/theme.json

@@ -20,8 +20,6 @@
         "secondary_button_hover": [85, 85, 87, 255],
         "secondary_button_text": [255, 255, 255, 255],
 
-        "tertiary_button_hover": [85, 85, 87, 255],
-
         "icon": [255, 255, 255, 255],
         "toolbar_background": [39, 44, 48, 255],
         "toolbar_button_active": [57, 57, 58, 255],

resources/themes/cura-light/theme.json

@@ -178,8 +178,6 @@
         "secondary_button_hover": [232, 240, 253, 255],
         "secondary_button_text": [25, 110, 240, 255],
 
-        "tertiary_button_hover": [232, 240, 253, 255],
-
         "main_window_header_background": [8, 7, 63, 255],
         "main_window_header_background_gradient": [25, 23, 91, 255],
         "main_window_header_button_text_active": [8, 7, 63, 255],