Fix soong_ui file rlimits for go 1.21

Go 1.21 modifies the file limit but restores the original when
execing subprocesses if it hasn't be overridden.  Call Setrlimit
even if it doesn't appear to be necessary so that the syscall package
considers it set.

Bug: 309895579
Test: m nothing
Change-Id: I4d0b27bac90a2a88bfc68a8491d54dc106e1ec13