cleanup: Prefer template strings

Template strings are much nicer than string concatenation, so use
them where possible; this excludes translatable strings and any
strings containing '/' (until we can depend on gettext >= 0.20[0]).

[0] https://savannah.gnu.org/bugs/?50920

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/612

js/misc/ibusManager.js

@@ -63,7 +63,7 @@ var IBusManager = class {
             Gio.Subprocess.new(['ibus-daemon', '--xim', '--panel', 'disable'],
                                Gio.SubprocessFlags.NONE);
         } catch (e) {
-            log('Failed to launch ibus-daemon: ' + e.message);
+            log(`Failed to launch ibus-daemon: ${e.message}`);
         }
     }