core(errors-in-console): properly define default options

[brendankenny]

fixes #10198

#11901 did the real fix, but didn't notice that #9480 had defined the previously empty defaultOptions as a static method and not a getter.

Classic case of unit vs integration tests:

• The upcoming work on overrides and getters/setters might catch this sort of thing in tsc in the future, but I'm not sure
• One way we could tackle this is exposing a way of "properly" running an audit with all the setup and teardown that audit-runner does and using that for all unit tests instead of calling .audit() directly. That would take care of context being initialized correctly and it would do the AuditProduct -> AuditResult transformation so tests could run on the real audit output expected in the LHR.