Update reference of old openjdk-systemtest to aqa-systemtest

[Mesbah-Alam]

We need to search for and update references to old openjdk-systemtest repo locations (both in doc and in scripts) and replace them with aqa-systemtest.

This should resolve the issue of systemtest failing to build on Grinder where a developer branch off of aqa-systemtest fork is used (e.g. #423 (comment))

[Mesbah-Alam]

Note: The 4 PRs related to this issue work fine when run in a grinder where there is no parallelism used. However, with parallelism, we encounter an issue in that the children jobs are checking out from openjdk-test repo off of master, not from the developer fork / branch.This issue should be fixed first before we can deliver these PRs.

@llxia : could you please have a look at the issue when you have some time? Thanks!