tsan: use smaller trace parts for Go

In the old runtime we used to use different number of trace parts
for C++ and Go to reduce trace memory consumption for Go.
But now it's easier and better to use smaller parts because
we already use minimal possible number of parts for C++ (3).

Reviewed By: melver

Differential Revision: https://reviews.llvm.org/D113978

GitOrigin-RevId: fa24d58279cf9a3e5a5ac894194808f4c1ad01f3
1 file changed