gitlab-ci: remove Ubuntu 19.10 from packing

Found issue on Tarantool package build for Ubuntu 19.10 [1]:

E: The repository 'http://archive.ubuntu.com/ubuntu eoan Release' does not have a Release file.
E: The repository 'http://archive.ubuntu.com/ubuntu eoan-updates Release' does not have a Release file.
E: The repository 'http://archive.ubuntu.com/ubuntu eoan-backports Release' does not have a Release file.
E: The repository 'http://security.ubuntu.com/ubuntu eoan-security Release' does not have a Release file.

Also found that time life of Ubuntu 19.04 ended with support [2]
on 17 of July 2020.

So packaging jobs for this OS removed from Gitlab-CI.

[1] - https://gitlab.com/tarantool/tarantool/-/jobs/902339975#L172
[2] - https://fridge.ubuntu.com/2020/07/17/ubuntu-19-10-eoan-ermine-end-of-life-reached-on-july-17-2020/#:~:text=Ubuntu%20announced%20its%2019.10%20(Eoan,updated%20packages%20for%20Ubuntu%2019.10.