[OMPT] Use __tsan_init to detect TSan binaries rather than RunningOnValgrind (#128357)
Switch to using __tsan_init rather than RunningOnValgrind as the means
for detecting TSan instumented binaries. RunningOnValgrind is present in
other libraries (such as Google perftools tcmalloc). An exe that links
with a tcmalloc static library and exports symbols with -rdynamic will
appear to be TSan instrumented even when it is not resulting in "Unable
to fint TSan function ..." messages.
Fixes issue #122319.