issue HPCINFRA-2469: [CI] remove support for old OS images

[vialogi]

issue: HPCINFRA-2469

Description

Remove support for old OS images

What

• removed ubuntu20.x
• removed branches running on r-aa-fatty22-005 and r-aa-fatty22-005 (rhel7,5 and ubuntu16.04 accordingly)

Why ?

Old OS versions are not supported by DOCA which we're going to switch to

How ?

Update job_matrix config

Change type

What kind of change does this PR introduce?

• [ ] Bugfix
• [ ] Feature
• [ ] Code style update
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [x] CI related changes
• [ ] Documentation content changes
• [ ] Tests
• [ ] Other