fix(tests): improve reliability of performance tests

[jpinkney-aws]

Problem

• We currently do a one-shot performance test measurement, which can be be impacted by the underlying cpu

Solution

• Run 5 performance tests by default, this should give us a more accurate reading

Performance of the last 10 test runs on my computer:

{userCpuUsage: 27.763992642839753, systemCpuUsage: 5.8700764000563925, duration: 0.0488549862, heapTotal: 0.15}
{userCpuUsage: 32.432557472712574, systemCpuUsage: 7.287778251185924, duration: 0.0350972354, heapTotal: 0.15}
{userCpuUsage: 36.17269595509756, systemCpuUsage: 8.190125881726889, duration: 0.0313357906, heapTotal: 0.15}
{userCpuUsage: 23.575720185158513, systemCpuUsage: 5.680905138190308, duration: 0.0468292694, heapTotal: 0.05}
{userCpuUsage: 29.722270663855547, systemCpuUsage: 6.725376761131834, duration: 0.044072017399999996, heapTotal: 0.05}
{userCpuUsage: 30.981420694546227, systemCpuUsage: 6.724871937232588, duration: 0.0404778744, heapTotal: 0.05}
{userCpuUsage: 29.15659118178076, systemCpuUsage: 6.544881314879868, duration: 0.0438601896, heapTotal: 0.15}
{userCpuUsage: 29.66190894781342, systemCpuUsage: 6.556456308274413, duration: 0.042828962400000004, heapTotal: 0.1}
{userCpuUsage: 32.209253755861006, systemCpuUsage: 7.245284221753529, duration: 0.036528329, heapTotal: 0.1}
{userCpuUsage: 30.4379237001285, systemCpuUsage: 6.790691656039722, duration: 0.0378142194, heapTotal: 0.1}
{userCpuUsage: 28.075430930361144, systemCpuUsage: 6.952612678963097, duration: 0.042763791, heapTotal: 0.1}

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.