The same skip is possible on retail as in MoP Remix.

The wall-to-ceiling connectors don't have a hitbox so you can just jump through them with a DH. You can reach them with a triple jump in the opposite direction followed by a backflip.

To clip back, check the comments of the same run performed by Keqing in MoP Remix. It uses a lag macro to hover in the air:

Items used:

• Wearing: Onyx Amulet with Wind Sculpting Stone, 3x Azerite Armor with the Longstrider trait, speed enchants
• Before entering: Bear Tartare, Charged Phial of Alacrity, Quickwick Candlestick (pre-cast)
• During run: Nitro Boosts, Gunshoes