Remove the unused mark duplicate as read preference. (#1448)

* Remove the unused mark duplicate as read preference.

* Migrate the old preference to new preference

app/src/main/java/eu/kanade/presentation/more/settings/screen/SettingsReaderScreen.kt

@@ -227,13 +227,6 @@ object SettingsReaderScreen : SearchableSettings {
                     preference = readerPreferences.skipDupe(),
                     title = stringResource(MR.strings.pref_skip_dupe_chapters),
                 ),
-                // SY -->
-                Preference.PreferenceItem.SwitchPreference(
-                    preference = readerPreferences.markReadDupe(),
-                    title = stringResource(SYMR.strings.pref_mark_read_dupe_chapters),
-                    subtitle = stringResource(SYMR.strings.pref_mark_read_dupe_chapters_summary),
-                ),
-                // SY <--
                 Preference.PreferenceItem.SwitchPreference(
                     preference = readerPreferences.alwaysShowChapterTransition(),
                     title = stringResource(MR.strings.pref_always_show_chapter_transition),

app/src/main/java/eu/kanade/tachiyomi/ui/reader/setting/ReaderPreferences.kt

@@ -184,8 +184,6 @@ class ReaderPreferences(
     fun centerMarginType() = preferenceStore.getInt("center_margin_type", PagerConfig.CenterMarginType.NONE)
 
     fun archiveReaderMode() = preferenceStore.getInt("archive_reader_mode", ArchiveReaderMode.LOAD_FROM_FILE)
-
-    fun markReadDupe() = preferenceStore.getBoolean("mark_read_dupe", false)
     // SY <--
 
     enum class FlashColor {