RFR: 8331118: Remove Serial includes from space.hpp

[Albert Mingkun Yang]

Remove Serial-specific logic from the `shared` folder.

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Commit messages:
 - space-header

Changes: https://git.openjdk.org/jdk/pull/18947/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18947&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331118
  Stats: 12 lines in 4 files changed: 2 ins; 10 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18947.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18947/head:pull/18947

PR: https://git.openjdk.org/jdk/pull/18947