[Release][CI] Use Ubuntu 24.04 for source verification jobs #50666

Describe the enhancement requested

Follow-up to #50600 and to temp fix #50649, aligned with #50414 :
Change verification images from Ubuntu 22.04 to Ubuntu 24.04,
and use the system provided Python 3.12 https://documentation.ubuntu.com/release-notes/24.04/

• verify-rc-source-cpp-linux-conda-latest-amd64
• verify-rc-source-integration-linux-conda-latest-amd64
• verify-rc-source-python-linux-conda-latest-amd64
• verify-rc-source-ruby-linux-conda-latest-amd64

Possibly remove these two Ubuntu 22.04 jobs from the matrix
verify-rc-source-integration-linux-ubuntu-22.04-amd64
verify-rc-source-python-linux-ubuntu-22.04-amd64
since equivalent Ubuntu 24.04 jobs already exist (verify-rc-source-integration-linux-ubuntu-24.04-amd64 and verify-rc-source-python-linux-ubuntu-24.04-amd64)

Also remove the Ubuntu 22.04 Miniforge workaround from #50649 where no longer required.

Component(s)

Continuous Integration, Release