[IDAG] Bump minimum hipSYCL and DPC++ versions

[fknorr]

The IDAG runtime needs updates to both the minimum hipSYCL and the minimum DPC++ version for proper reduction support and various bugfixes.

This PR bumps both versions and adjusts documentation accordingly, also mentioning the recently found OpenMPI < 4.0.2 bug which is already relevant when running mpi_tests today. An older workaround on sycl::item still required for the old pinned version of hipSYCL is now obsolete and is also removed.

As the most recent version of hipSYCL does not build with LLVM 10 anymore, this change also drops support for Ubuntu 20.04. We plan to automate testing on 24.04 as soon as Nvidia releases a CUDA docker image for that distribution.

[github-actions[bot]]

Check-perf-impact results: (7b849de16ff11660b98988ab0b032db7)

:question: No new benchmark data submitted. :question:
Please re-run the microbenchmarks and include the results if your commit could potentially affect performance.

[coveralls]

Pull Request Test Coverage Report for Build 9724735193

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 94.703%

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Totals
Change from base Build 9661291153:	0.03%
Covered Lines:	7052
Relevant Lines:	7266

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💛 - Coveralls

[fknorr]

I have used the opportunity to upgrade our CI setup to test with Ubuntu 24.04 while keeping compatibility with 22.04, and dropping 20.04. This required some minor fixes to bridge OS version differences. I have left 22.04 as the benchmark base image to avoid re-running those.