tests: Make probe.tracepoint_data_loc less flaky
tests: Make probe.tracepoint_data_loc less flaky

I was seeing some flakiness on my dev machine for this test (test would
hang). I'm guessing it's b/c the perf buffer was so overloaded with
events it took a while to drain.

Should be good enough to exit after one sample. Would be weird for an
irq handler to have a single character name.

iovisor/bpftrace,iovisor/bpftrace,iovisor/bpftrace,iovisor/bpftrace