ctf: Make sure CTFTraceTest's are independent

ctf: Make sure CTFTraceTest's are independent

The getClock() tests would use the value set by a previous test.
Remedy that by merging the getter and setter tests. Also cleaned
up the file a bit while a it.

Change-Id: I10df9ae5960ae426e607eb92b5a3956bb90a158d
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/11162
Tested-by: Hudson CI
Reviewed-by: Bernd Hufmann <bhufmann@gmail.com>
IP-Clean: Bernd Hufmann <bhufmann@gmail.com>
Tested-by: Bernd Hufmann <bhufmann@gmail.com>