Open links to social networks in the same window

As mentioned in earlier commits, opening external links in a new
tab/window results in usability and accessibility issues.

Since these links are usually at the top or bottom of the page and
contain icons of well-known sites, IMHO there's no need to even notify
people that these are external links.

Since we're no longer using the `shared.target_blank` translation inside
a sentence, we can remove the space and parenthesis in the translations.

app/components/layout/social_component.rb

@@ -18,7 +18,7 @@ class Layout::SocialComponent < ApplicationComponent
     end
 
     def link_title(site_name)
-      t("shared.go_to_page") + link_text(site_name) + t("shared.target_blank")
+      t("shared.go_to_page") + link_text(site_name)
     end
 
     def link_text(site_name)