stats: Test we do correctly invalidate the sorted array
stats: Test we do correctly invalidate the sorted array

Chris had a doubt, and I was lazy and didn't do a similar test for the
quartiles/median than for the mean (test_invalidate_mean()). Plug that
gap.

Signed-off-by: Damien Lespiau <64bd3cb94f359c1a3ce68dae5e26b40578526277@intel.com>

tiagovignatti/intel-gpu-tools,dlespiau/checkmate-test-igt,chenxianqin/intel-gpu-tools,mv0/intel-gpu-tools,mv0/intel-gpu-tools,chenxianqin/intel-gpu-tools,chenxianqin/intel-gpu-tools,tiagovignatti/intel-gpu-tools,dlespiau/checkmate-test-igt,chenxianqin/intel-gpu-tools,dlespiau/checkmate-test-igt,tiagovignatti/intel-gpu-tools,mv0/intel-gpu-tools,mv0/intel-gpu-tools,dlespiau/checkmate-test-igt,tiagovignatti/intel-gpu-tools