[INTERNAL] Splits logging config for testing

saros.log4j.properties is loaded explicitly for regular execution.
log4j.properties is loaded when tests are executed where a logger is
requested to accessing the IntelliJ log directory.

Change-Id: Id4949ef4bda58657c5b1d5c93a3268b5c567147f
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/2031
Tested-by: Jenkins CI
Reviewed-by: Holger Schmeisky <google@schmeisky.com>