[Perf] Display results with 4 significant figures

[mikeharder]

Before

Completed 7,421 operations in a weighted-average of 5.00s (1,482.92 ops/s, 0.001 s/op)

Test	Arguments	12.11.0	source	%Change
download	--size 10240 --parallel 64	1991.58	1911.60	-4.02%
download	--size 10485760 --parallel 32	144.92	145.36	0.30%
download	--size 10485760 --parallel 32 --sync	-1.00	-1.00	0.00%
download	--size 1073741824 --parallel 1 --warmup 60 --duration 60	0.17	0.18	5.88%
download	--size 1073741824 --parallel 8 --warmup 60 --duration 60	1.24	1.25	0.81%

After

Completed 7,392 operations in a weighted-average of 4.999s (1,479 ops/s, 0.0006763 s/op)

Test	Arguments	12.11.0	source	%Change
download	--size 10240 --parallel 64	1,974	1,881	-4.71%
download	--size 10485760 --parallel 32	147.6	141.7	-4.00%
download	--size 1073741824 --parallel 1 --warmup 60 --duration 60	0.1398	0.1461	4.51%
download	--size 1073741824 --parallel 8 --warmup 60 --duration 60	1.069	1.092	2.15%

Validation Build

https://dev.azure.com/azure-sdk/internal/_build/results?buildId=1743984&view=results