Revert PR #3359 as this is breaking stuff for many folks. Need to rethink how we handle system defaults differently on this
fix(tools/check_for_upgrade): Don't source profile

Reverts #2296, but mostly #1883.

There is no need to source ~/.profile when this script is read. oh-my-zsh writes no configuration data in ~/.profile.

If the user wishes to use data within ~/.profile, then they should source it in another place.

Fixes #2315