RFR: 8300732: Whitebox functions for Metaspace test should use byte size [v3]

[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

Sonia Zaldana Calles has updated the pull request incrementally with one additional commit since the last revision:

  Feedback - updating Unit.valueOf to direct access

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/20039/files
  - new: https://git.openjdk.org/jdk/pull/20039/files/7c0138ca..d6a1155d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20039&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20039&range=01-02

  Stats: 6 lines in 3 files changed: 0 ins; 0 del; 6 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