javacore dumps should not be written to Zowe runtime directory

[John-A-Davies]

Describe the bug
An out-of-memory error occurred, which caused java core, heap and snap dumps to be written to the Zowe runtime directory. This directory is supposed to be read-only.

To Reproduce
Steps to reproduce the behavior:

1. Refer to issue out-of-memory error on large dataset #161

Expected behavior
Dumps should be written to the instance directory, not the runtime directory.

Additional context

1. Writing to this location compromises our ability to verify the authenticity of the Zowe driver, see Provide a way to verify the authenticity of a Zowe driver as being original, untampered, release zowe-install-packaging#1179
2. Java options are available to direct dump output to a nominated directory

[John-A-Davies]

@stevenhorsman @jordanCain FYI.