Fix sporadic false failure in xprofile unit test code (master)

Same fix as is going through on feature/ec, fixed it there first
as it was happening often and no point in waiting until EC is
complete before getting it over to master...

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: I958f1525c2727b3fb3f533242fa509fa8e59926c
Merge "Fix sporadic false failure in xprofile unit test code (master)"