`t2w_preproc` query not specified in `io_spec.json`

[tsalo]

Describe the bug
The key t2w_preproc is looked for in init_anat_fit_wf, but there is not query for it in io_spec.json. I looked at collect_derivatives. While t1w_ is automatically prepended to the queries in the "base" group, there doesn't seem to be any equivalent step for t2w data.