Remove ubuntu/eoan package

Overview

The ubuntu/eaon (19.10) reached end of life in July 2020. We should remove the distribution of this package.

Proposal

Update the following lines to remove distribution of ubunu/eaon:

https://gitlab.com/gitlab-org/gitlab-runner/-/blob/79c4a7889bd1e1953dac5d20a4b7f73862bae24a/Makefile#L22 https://gitlab.com/gitlab-org/gitlab-runner/-/blob/79c4a7889bd1e1953dac5d20a4b7f73862bae24a/ci/release_packagecloud#L9