[release/6.0] Cleaned up version of earlier PR #48601. (#58544)

[release/6.0] Cleaned up version of earlier PR #48601. (#58544)

* Cleaned up version of earlier PR #48601.

* Address code review feedback.

* Take out changes in dt_high_frag_p - probably no longer necessary.

Remove changes for the heap_hard_limit case - we'll do those later.

Fixed another place where I had called generation_sizes instead of generation_size.

* Fixed parameter for call to generation_size.

* Update comment to the more explicit version in .NET Framework.

* Added parentheses around an expression to address code review feedback.

Co-authored-by: Peter Sollich <petersol@microsoft.com>