fix: restore original default value for "messagelist_colorize_missing_contact_pictures" after migration to new PreferenceManager

Author: shamim-emon

core/preference/api/src/commonMain/kotlin/net/thunderbird/core/preference/display/visualSettings/DisplayVisualSettings.kt

@@ -3,7 +3,7 @@ package net.thunderbird.core.preference.display.visualSettings
 const val DISPLAY_SETTINGS_DEFAULT_IS_SHOW_CONTACT_NAME = false
 const val DISPLAY_SETTINGS_DEFAULT_IS_SHOW_CONTACT_PICTURE = true
 const val DISPLAY_SETTINGS_DEFAULT_IS_CHANGE_CONTACT_NAME_COLOR = true
-const val DISPLAY_SETTINGS_DEFAULT_IS_COLORIZE_MISSING_CONTACT_PICTURE = false
+const val DISPLAY_SETTINGS_DEFAULT_IS_COLORIZE_MISSING_CONTACT_PICTURE = true
 const val DISPLAY_SETTINGS_DEFAULT_IS_USE_BACKGROUND_AS_INDICATOR = false
 const val DISPLAY_SETTINGS_DEFAULT_IS_USE_MESSAGE_VIEW_FIXED_WIDTH_FONT = false
 const val DISPLAY_SETTINGS_DEFAULT_IS_AUTO_FIT_WIDTH = true