check back-transformation on yi euc meta-analysis

[egouldo]

• [x] ensure that plots for euc variables don't repeat back-transformations unnecessarily (meta-analysis should already be on stem-count scale, i.e. not standardised as per Z_VZ_preds()), however, we should continue logging the outcome variable.
• [ ] Ensure (if) any logging of response vars is done prior to fitting models, that these are reported as a deviation in manuscript (I think we only transform them for plotting purposes).
• [ ] Update preregistration deviation section. See issue in non-anonymised repository for discussion / paper-trail on decision: https://github.com/metamelb-repliCATS/ManyAnalysts/issues/194

[egouldo]

• [ ] When egouldo/ManyEcoEvo#88 is closed, this issue can be addressed.

[egouldo]

• [ ] Note, need to shift log-transformation (if needed) into ManyEcoEvo pkg.
• [x] first, try running plot on non-standardised but back-transformed data