Mast job launcher overrides library defaults and cause surprises to the user

[pzhan9]

Monarch overrides a bunch of defaults, instead of using the library's own defaults: https://fburl.com/code/uh4mdjvw

e.g.

"NVTE_FUSED_ATTN_USE_FAv2_BWD": "1",

this has caused surprises for the internal users several times, since they assumed it would be library defaults, and there does not seem to be anyway to tell them they are overridden. So they found it out in a hard way.

related chats:

https://chat.google.com/room/AAQAkhyUiVg/laBYD7BB5aQ/laBYD7BB5aQ?cls=10
https://chat.google.com/room/AAQA8ub_cFI/okyhzzykxuU/okyhzzykxuU?cls=10

[pzhan9]

Landed with D90210273