Accept conda channels' ToS with environment variable. (#9666)
Follow-up: #9661
Apparently, we need to accept the ToS of those same channels, again
([link](https://github.com/pytorch/xla/actions/runs/18172128014/job/51729124142)).
Instead, I'm using the `CONDA_PLUGINS_AUTO_ACCEPT_TOS` environment
variable, documented
[here](https://github.com/pytorch/pytorch/issues/158438#issuecomment-3084935777).
