Add better apt sources

[rotu]

Description

The default runners in Github actions use pretty bad apt sources, causing unnecessary CI failures.

For example this pull request, which updates just a readme causes build failures because azure's Ubuntu mirror is flaky: https://github.com/ros-tooling/action-ros-ci/pull/129/checks?check_run_id=553125397.

I work around this in ros2/rmw_cyclonedds#134 but this repo is probably a better place to solve the problem so all downstream CI workflows don't have the same reliability problems.

2020-04-01T20:20:23.8861478Z ##[group]Invoking "sudo apt-get update"
2020-04-01T20:20:23.8867344Z [command]sudo apt-get update
...
2020-04-01T20:20:54.7635136Z Err:39 http://azure.archive.ubuntu.com/ubuntu bionic InRelease
2020-04-01T20:20:54.7635929Z   Could not connect to azure.archive.ubuntu.com:80 (52.177.174.250), connection timed out
...
2020-04-01T20:22:12.2857474Z [command]sudo DEBIAN_FRONTEND=noninteractive RTI_NC_LICENSE_ACCEPTED=yes apt-get install --no-install-recommends --quiet --yes libssl-dev python3-dev build-essential clang cmake git lcov libc++-dev libc++abi-dev python3-catkin-pkg-modules python3-pip python3-vcstool wget libasio-dev libtinyxml2-dev libopensplice69 rti-connext-dds-5.3.1 python-rosdep
...
2020-04-01T20:22:43.1336618Z E: Failed to fetch http://azure.archive.ubuntu.com/ubuntu/pool/main/s/sgml-base/sgml-base_1.29_all.deb  Could not connect to azure.archive.ubuntu.com:80 (52.177.174.250), connection timed out

[christophebedard]

I don't think I've seen this happen recently. Is this still an issue?

[emersonknapp]

I have also not seen this happen recently - I think the internal azure infrastructure might have stabilized a little. I'll close as stale for now, but please anybody reopen if you still see this issue.