RFR: 8326065: Merge Space into ContiguousSpace

[Stefan Johansson]

On Fri, 16 Feb 2024 17:00:15 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Merging a super class into its single sub class.
> 
> Test: tier1-6

Looks good, feels like the files should change name as well. Now when there no longer is a `Space`. But maybe that's even better to do once we have moved `TenuredSpace` into Serial. 

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Marked as reviewed by sjohanss (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17891#pullrequestreview-1897558605