[Onion Services] Remove how to install tor page

We should remove this page how to install tor: https://community.torproject.org/onion-services/setup/install/ and add a note here https://community.torproject.org/onion-services/setup/, pointing to the new Support portal page: https://support-b46ee3.pages.torproject.net/little-t-tor/getting-started/installing/, which include all the instructions.

cc jfyi @rhatto