[Plasma] Unmap memory when the client is destroyed #21485
Description
Currently the plasma memory mapped into the client is not unmapped upon destruction of the client, which can cause memory mapped files to be kept around longer than necessary.
Reporter: Philipp Moritz / @pcmoritz
Assignee: Philipp Moritz / @pcmoritz
PRs and other links:
Note: This issue was originally created as ARROW-4983. Please see the migration documentation for further details.