Update icon and label of reactions button

They've been updated in the designs.

locales/en-GB/app.json

@@ -12,7 +12,6 @@
     "no": "No",
     "pick_reaction": "Pick reaction",
     "raise_hand": "Raise hand",
-    "raise_hand_or_send_reaction": "Raise hand or send reaction",
     "register": "Register",
     "remove": "Remove",
     "show_less": "Show less",
@@ -62,6 +61,7 @@
     "preferences": "Preferences",
     "profile": "Profile",
     "reaction": "Reaction",
+    "reactions": "Reactions",
     "settings": "Settings",
     "something_went_wrong": "Something went wrong",
     "unencrypted": "Not encrypted",