TBB's Startpage search plugin has a different name (Closes: #8036)

... than the old one we used prior to the TBB migration, so our
branding addons wouldn't set it as the default for en-US (and locales
without a localized Startpage plugin, which falls back to en-US).

config/chroot_local-includes/usr/local/share/tor-browser-extensions/branding@amnesia.boum.org/chrome/locale/ar-EG/amnesia.properties

-browser.search.defaultenginename=Startpage HTTPS
-browser.search.selectedEngine=Startpage HTTPS
+browser.search.defaultenginename=Startpage
+browser.search.selectedEngine=Startpage
 browser.startup.homepage=https://tails.boum.org/news/
 spellchecker.dictionary=ar_EG

config/chroot_local-includes/usr/local/share/tor-browser-extensions/branding@amnesia.boum.org/chrome/locale/en-US/amnesia.properties

-browser.search.defaultenginename=Startpage HTTPS
-browser.search.selectedEngine=Startpage HTTPS
+browser.search.defaultenginename=Startpage
+browser.search.selectedEngine=Startpage
 browser.startup.homepage=https://tails.boum.org/news/
 spellchecker.dictionary=en_US

config/chroot_local-includes/usr/local/share/tor-browser-extensions/branding@amnesia.boum.org/chrome/locale/zh-CN/amnesia.properties

-browser.search.defaultenginename=Startpage HTTPS
-browser.search.selectedEngine=Startpage HTTPS
+browser.search.defaultenginename=Startpage
+browser.search.selectedEngine=Startpage
 browser.startup.homepage=https://tails.boum.org/news/
 spellchecker.dictionary=en_US