RFR: 8300732: Whitebox functions for Metaspace test should use byte size

[Sonia Zaldana Calles]

Hi all, 

This PR addresses [8300732](https://bugs.openjdk.org/browse/JDK-8300732) switching Whitebox Metaspace test functions to use bytes as opposed to words. 

Testing: 
- [x] `test/hotspot/jtreg/runtime/Metaspace` tests pass. 

Thanks, 
Sonia

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Commit messages:
 - 8300732: Whitebox functions for Metaspace test should use byte size

Changes: https://git.openjdk.org/jdk/pull/20039/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20039&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8300732
  Stats: 140 lines in 12 files changed: 48 ins; 0 del; 92 mod
  Patch: https://git.openjdk.org/jdk/pull/20039.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20039/head:pull/20039

PR: https://git.openjdk.org/jdk/pull/20039