Further improve mergebot messages (#84283)
Reword the rejection reasons to better match the format mergebot uses to output the message, and repoints the workflow links to point to the commit page in hud instead of github
**Context:** Some of the mergebot messages looked a bit weird. For example, it would claim to be offering a reason for a merge failing, but instead the message would be of a more diagnostic nature.
Example of a weird message ("view failures on hud" is not a reason!):
<img width="960" alt="image" src="https://user-images.githubusercontent.com/4468967/187495195-9f1cf6cc-49e3-42a1-8c29-b1e95027d0e2.png">
The above message would now look like:
<img width="967" alt="image" src="https://user-images.githubusercontent.com/4468967/187726065-ea93dc34-065f-47bd-acd4-78415329e5a6.png">
Pull Request resolved: https://github.com/pytorch/pytorch/pull/84283
Approved by: https://github.com/huydhn
