Use the correct channel token when uploading nightly triton conda (#109073)
This fixes 2 bugs on triton build workflow:
* Use the wrong conda credential when `UPLOAD_CHANNEL` is not set https://github.com/pytorch/pytorch/actions/runs/6129675580/job/16691419329#step:7:18
* Upload wheel and conda packages when pushing to main in addition to nightly. This is needed because the binary wheel build on trunk also looks for torchtriton package after the triton pin is updated.
### Testing
https://github.com/pytorch/pytorch/actions/runs/6152447684/job/16694843862?pr=109073#step:7:38 looks correct now.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/109073
Approved by: https://github.com/atalman
