Refactor: tools: Don't ignore invalid format in reconcile_output_formats

If --output-as is unspecified (pcmkstr_null_matches), then default to
"console". But if we get some nonsense like "asdf", don't use the
default. Let pcmkoutput_new() try to create the output object and
fail.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>