Fix sporadic false failure in xprofile unit test code

Appears that what's been happening on feature/ec lately
with a middleware failure has to do with a hardcoded PID in
the test code itself causing a profile file to exist when
its not expected to by the test...

Test code used a PID of 135 and based on how get_logfiles()
is written, any real PID that starts with 135 will cause a
false failure in test_call().  This can be seen via inspection
and confirmed in logfiles where all captured assertions show
a profile filename beginning with 135.  Tried getting smarter
about choosing a fake PID (int) but then decided it was 100%
safe to use 'ABC' for this test since that'll never show up!

Change-Id: I61adc36a127a5b362b2983f94c58dd9be3a9b13d
Merge "Fix sporadic false failure in xprofile unit test code" into feature/ec