BLD: various test_perf fixes
- The git ref parsing didn't handle annotated tags well, returning a bad hash
  if you tried `test_perf -t HEAD -b v0.13.0` and got a weird error, fixed. (git weirdness, fyi @cpcloud)
- try to Disable frame_expand_repr when printing stats, pasting results for comparison is much easier
  that way.
- Added --temp-dir to name a specific (rather then randomized) scratch directory for vbench,
  the randomized temp. dir was preventing ccache from doing it's job.  Highly recommended
  that you always invoke test_perf with a consistent `--temp-dir my-benching-dir`. This took down
  the comparative runs from 5 minutes to less then 60 seconds on my box. cc @jreback, @yarikoptic.

xref https://github.com/pydata/pandas/issues/6199
