[Perf] Display results with 4 significant figures

[mikeharder]

Before

Completed 141,743 operations in a weighted-average of 14.96s (9,473.74 ops/s, 0.000 s/op)

Test	Arguments	12.18.0	source	%Change
download	--size 10240 --parallel 64 --warmup 15 --duration 15	15155.43	15351.79	1.30%
download	--size 10485760 --parallel 32 --warmup 15 --duration 15	172.42	172.99	0.33%
download	--size 10485760 --parallel 32 --sync --warmup 15 --duration 15	177.55	177.09	-0.26%
download	--size 1073741824 --parallel 1 --warmup 60 --duration 60	0.27	0.28	3.70%
download	--size 1073741824 --parallel 8 --warmup 60 --duration 60	1.73	1.74	0.58%

After

Completed 131,408 operations in a weighted-average of 14.96s (8,785 ops/s, 0.0001138 s/op)

Test	Arguments	12.18.0	source	%Change
download	--size 10240 --parallel 64 --warmup 15 --duration 15	14,361	14,872	3.56%
download	--size 10485760 --parallel 32 --warmup 15 --duration 15	170.5	172.3	1.06%
download	--size 10485760 --parallel 32 --sync --warmup 15 --duration 15	174.8	175.1	0.17%
download	--size 1073741824 --parallel 1 --warmup 60 --duration 60	0.2262	0.2232	-1.33%
download	--size 1073741824 --parallel 8 --warmup 60 --duration 60	1.696	1.686	-0.59%

Validation Build

https://dev.azure.com/azure-sdk/internal/_build/results?buildId=1743983&view=results