4d2fb64ac2
Running `./mach perftest` gives errors or surprising behaviour, and is generally unmaintained. Remove the no-arguments behaviour and leave specific test runner scenarios. The `./mach try perf` tools is the recommended way to run perf tests on CI these days. Differential Revision: https://phabricator.services.mozilla.com/D239266
=========== mozperftest =========== **mozperftest** can be used to run performance tests against browsers. See the docs directory.