Fix new sonars in drools-apps

Fix new sonars in drools-apps

Addressed the following sonars:
- too many assertions in test method
- rename test class
- use static method to modify static field
- use already defined constant
- code always returns the same value
- use assertNotSame
- use appropriate class name to access static method
- define a constant
- extract nested try block
- don't always return the same value
- use remove() instead of set(null) for thread-local-storage
- add @Override

Issue-ID: POLICY-2852
Change-Id: Icc62acd4ad57afa2d44ed4cdca504a3ac0810228
Signed-off-by: Jim Hahn <jrh3@att.com>