[DeepSpeed] fix flag forwarding in DeepSpeedPlugin

[jona-0]

What does this PR do?

Forward the cpu_checkpointing and contiguous_memory_optimization flags of DeepSpeedPlugin to deepspeed correctly. Previously we were ignoring these flags.

Fixes #10874

Before starting this issue I did not realize that contiguous_memory_optimization was also not forwarded, but the unit test showed it had a similar issue as cpu_checkpointing

Does your PR introduce any breaking changes? If yes, please list them.

I don't think so, but could do if deepspeed sometimes has problems with these flags (not found myself and I think this should be the expected behaviour).

Before submitting

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PR review

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Did you have fun?

Yes 🙃

[SeanNaren]

Looks great, and appreciate the additional test!

[codecov]

Codecov Report

Merging #10899 (55b2b45) into master (46f718d) will decrease coverage by 4%.
The diff coverage is n/a.

❗ Current head 55b2b45 differs from pull request most recent head cc3cf91. Consider uploading reports for the commit cc3cf91 to get more accurate results

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- Hits        15162    14541   -621     
- Misses       1359     1980   +621