FIX: Swap direction of fmap-EPI transform

[effigies]

Changes proposed in this pull request

#3099 introduced a subtle bug where we applied the inverse transform of what we needed. This is because init_unwarp_wf and init_coeff2epi_wf have opposite conventions (point and image) for describing transforms.

This could be swapped in sdcflows, but I intend to replace unwarp_wf with our resampler, so this is just doing the job correctly in the meantime.

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (511c838) 47.24% compared to head (3688554) 47.24%.

Additional details and impacted files

@@           Coverage Diff           @@
##             next    #3106   +/-   ##
=======================================
  Coverage   47.24%   47.24%           
=======================================
  Files          49       49           
  Lines        4009     4009           
=======================================
  Hits         1894     1894           
  Misses       2115     2115           

Files	Coverage Δ
fmriprep/workflows/bold/fit.py	25.00% <ø> (ø)

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.