Bug 453275 - Codan tests cannot test for checkers throwing an exception

Added system flag that is used to propagate exception
instead of swallowing. Set by default in codan junit tests.

Change-Id: Iccda9a7b2e419192bb9f4eec4b89d525e152fc81
Signed-off-by: Alena Laskavaia <elaskavaia.cdt@gmail.com>
Reviewed-on: https://git.eclipse.org/r/37482