test: use common.expectsError()

Use common.expectsError() instead of rolling own validation function in
test-http-request-invalid-method-error.js. common.expectsError() didn't
exist when the test was written, but now it does.

PR-URL: https://github.com/nodejs/node/pull/11408


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>