Fix not being able to upload GIF emojis in admin UI (#17759)

app/views/admin/custom_emojis/new.html.haml

config/locales/ar.yml

config/locales/bn.yml

config/locales/ca.yml

config/locales/co.yml

config/locales/cs.yml

config/locales/cy.yml

config/locales/da.yml

config/locales/de.yml

config/locales/el.yml

config/locales/en.yml

config/locales/en_GB.yml

config/locales/eo.yml

config/locales/es-AR.yml

config/locales/es-MX.yml

config/locales/es.yml

config/locales/et.yml

config/locales/eu.yml

config/locales/fa.yml

config/locales/fi.yml