TCK Truffle tests are leaking memory

[hubertp]

As revealed in the investigation related to memory leaks.

Looks like running runtime-integration-tests with TCK tests leads to an increased memory usage for the duration of its run i.e. old objects are not GC'ed. This bumps memory usage by up to roughly 1GB and we only have a small number of those tests.

[JaroslavTulach]

• I have noticed the strange TCK test behavior in Verify EnsoContext can be GCed after cleaning up ContextUtils rule #14219 too
• as far as I can say everything get GCed after the TCK part of test suite is over
• e.g. it is not really a leak I think
• if our runners can keep with this extra large memory needed by TCK, we can probably live with it