[Other][Dev] Remove remnants for Ubuntu 20.04

[raulcd]

Describe the enhancement requested

We did drop support for Ubuntu 20.04 but I've found a couple remnants that seem still related to it.

• [CI][C++] Drop support for Ubuntu 20.04 #45478

We should clean those up. I'll follow up with a PR.

Component(s)

Other, Developer Tools

[kou]

Issue resolved by pull request 50413
#50413