RFR: 8369041: Release memory after testing in ThreadsRunner.java

[Aleksey Shipilev]

On Thu, 2 Oct 2025 11:16:09 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Small patch of cleaning up no longer used data structures after testing is complete. 
> 
> Test: tier1-5

Feels like these cleanup calls belong in `finally` block, so that they get cleaned up even on exception?

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PR Review: https://git.openjdk.org/jdk/pull/27606#pullrequestreview-3303123306