RFR: 8296919: Make system tests that detect memory leaks more robust by using JMemoryBuddy utility [v3]

[Andy Goryachev]

On Wed, 3 May 2023 09:20:14 GMT, Lukasz Kostyra <lkostyra at openjdk.org> wrote:

>> Verified these changes on all platforms and saw no abnormalities in test execution.
>> 
>> This change is based on a preliminary patch done by @aghaisas , with some minor changes and the addition of one Leak-related web test. EventListenerLeak test was not touched, as it is a separate manual test app instead of a JUnit test.
>
> Lukasz Kostyra has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Minor review updates
>   
>   * Changed ArrayList<> to Collection<> in one of assertCollectable-s
>   * Updated LeakTest to use new assertCollectable helpers

looks good, one .classpath file change is requested.

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Changes requested by angorya (Committer).

PR Review: https://git.openjdk.org/jfx/pull/1121#pullrequestreview-1411606552