The concurrency tests introduced in SERVER-16196 use ScopedThreads to run workloads. These ScopedThreads (intentionally) leak JSThreadConfig data, which eventually leads to build failures on VMs with limited RAM.

We need to delete the JSThreadConfig data to keep the memory footprint of the shell reasonable during the tests:

https://github.com/mongodb/mongo/blob/9db6b7d7ad6e585f9bc9b0779db10d53535b4b68/src/mongo/scripting/v8_utils.cpp#L313-L317

https://github.com/mongodb/mongo/blob/9db6b7d7ad6e585f9bc9b0779db10d53535b4b68/src/mongo/scripting/v8_utils.cpp#L323-L327