RFR(XS): 8144536: Clean up Unified Logging test directory

[Rachel Protacio]

Hi,

I have a short cleanup of the test/runtime/logging directory, 
consolidating two options' tests into one file each. Also improved the 
@run directives as per the recent emails on the topic.

Open webrev: http://cr.openjdk.java.net/~rprotacio/8144536/
Bug: https://bugs.openjdk.java.net/browse/JDK-8144536
Testing: The tests still succeed with jtreg.

Thank you!
Rachel