[ET-VK] Modify quantized linear tiling shader to linearly dispatch work to improve thread occupancy and performance. (#10508)

Stack from [ghstack](https://github.com/ezyang/ghstack) (oldest at
bottom):
* #10509
* __->__ #10508

This diff changes tiled 8 bit quantized linear mat mul op to linearly
dispatch work which increases thread occupancy and improves performance.

Differential Revision:
[D73751979](https://our.internmc.facebook.com/intern/diff/D73751979/)