Channel `latest/edge` is unmaintained and should be delisted

[motjuste]

Filed on behalf of @@canonical/solutions-qa

The latest/edge channel currently published in Charmhub points to revision 89 (and 9! on Ubuntu 20.04). This channel seems unmaintained and should be delisted if there are no plans to update it.

[motjuste]

Hi team! Is there any reason we still have latest/edge listed in Charmhub?