Revert any accidental transition class removals

This comment thread (!167802 (comment 2139758132)) pointed out that we may have been accidentally removing Vue transition classes as part of this epic's initiative &15017 (closed)

As a consequence, this report (https://docs.google.com/spreadsheets/d/1mDOkHTG7ILz2z0Ndf9NpnXvm-c0KsaMVtTc5X3uvVKM/edit?gid=19499608#gid=19499608) was made to investigate each line of code removed as part of the epic and I searched through it for accidental removals related to Vue transitions, there were the only ones found !164657 (diffs)