All WB functions pertaining to elastic metaspace that take sizes take those in number-of-words.

`WB_CreateMetaspaceTestContext`,
`WB_AllocateFromMetaspaceTestArena`, `WB_DeallocateToMetaspaceTestArena`,
`WB_GetTotalCommittedWordsInMetaspaceTestContext`, `WB_GetTotalUsedWordsInMetaspaceTestContext`
 and
`WB_GetMaxMetaspaceAllocationSize`.

This is unwieldy, and since the tests using them (test/hotspot/jtreg/runtime/Metaspace/elastic/Settings.java) implicitly assume 8 as word size, slightly wrong for 32-bit.

The error is benign since these sizes are applied consistently. But it makes maintenance difficult.