Do not call conda with --freeze-installed or --no-channel-priority

The --no-channel-priority is only relevant when using the development/internal channels, and also may cause problems if we ever end up with package name collisions between the FSL channels and conda-forge.

And the --freeze-installed option frequently causes conda to fail. In particular, conda seems to dislike being asked to install/update anything if it is not allowed to update openssl, certifi, and ca-certificates (which it can't do when called with --freeze-installed).