Drop quick exit feature

Broken now due to multiple navigation destinations unlike before
when there were only 3 fragments were the only choices.

Quick exit is supposed to be now the default behaviour in the coming commits

Signed-off-by: Aayush Gupta <aayushgupta219@gmail.com>

app/src/main/res/values-lv/strings.xml

@@ -130,7 +130,6 @@
     <string name="pref_ui_theme_darkord">Discord</string>
     <string name="pref_ui_theme_title">Motīvs</string>
     <string name="pref_ui_layout_tab">Izvēlēties noklusējuma lapu</string>
-    <string name="pref_ui_quick_exit_desc">Pamest lietotni ar vienu atpakaļ pogas nospiešanu</string>
     <string name="pref_ui_no_for_you">For You lapa</string>
     <string name="pref_ui_no_for_you_desc">Rādīt For You lapu sākuma ekrānā</string>
     <string name="pref_ui_similar_apps">Līdzīgas un saistītas lietotnes</string>
@@ -146,7 +145,6 @@
     <string name="title_updates">Atjauninājumi</string>
     <string name="title_manual_download">Pašrocīga lejupielāde</string>
     <string name="toast_purchase_blocked">Lietotņu pirkumi anonīmos kontos nav pieejami.</string>
-    <string name="toast_double_press_to_exit">Spiediet divreiz, lai izietu</string>
     <string name="purchase_unsupported">Lietotne nav atbalstīta</string>
     <string name="tab_categories">Kategorijas</string>
     <string name="tab_top_grossing">Top pārdošanā</string>
@@ -195,7 +193,6 @@
     <string name="pref_filter_google_summary">Noņem visas Google lietotnes no meklēšanas rezultātiem</string>
     <string name="pref_filter_google_title">Filtrēt Google lietotnes</string>
     <string name="pref_ui_theme_dark">Tumšs</string>
-    <string name="pref_ui_quick_exit">Ātri pamest lietotni</string>
     <string name="pref_ui_theme_dark_x">Tumšs X</string>
     <string name="pref_ui_theme_system">Sekot sistēmai</string>
     <string name="pref_ui_title">Pielāgošana</string>