Auto Upgrade script should not hardcode repo name

[programmerq]

Expected behavior:

Teleport upgrader should work even if the teleport package is not from a repository name "teleport"

Some companies have policies about installing packages from Satellite or from an Artifactory mirror rather than a vendor's upstream repository.

Current behavior:

The automatic upgrade script appears to reference the yum "teleport" repository or the apt "sources.list.d/teleport.list" source.

It should be possible to specify the repository or source to expect.

Bug details:

• Teleport version - 13.3.2

Aug 22 14:53:30 teleport-upgrade[53901]: Error getting repository data for teleport, repository not found