fix colorbar suppression when vlim is joint

[drammock]

Fixes bug reported on the forum: https://mne.discourse.group/t/how-to-suppress-redundant-colorbars-when-using-epochsarray-plot-psd-topomap/7338

[larsoner]

Looks like the default is colorbar=False which might explain why the tutorial has no colorbar

https://output.circle-artifacts.com/output/job/a2b760da-5862-4658-bf9e-0082d15d00c9/artifacts/0/html/auto_tutorials/epochs/20_visualize_epochs.html#sphx-glr-auto-tutorials-epochs-20-visualize-epochs-py

So it looks the same as on main

https://mne.tools/dev/auto_tutorials/epochs/20_visualize_epochs.html#sphx-glr-auto-tutorials-epochs-20-visualize-epochs-py

That being said I think they both look okay and the code looks okay, so if you agree this (still) does not need a colorbar then +1 for merge from me based on my having looked at the code (it should do the right thing I think)

FWIW at some point we could switch this to use constrained_layout and just add a fig.colorbar rather than using this ai == len(axes) - 1 or whatever. But that would be for another PR I think :)

[drammock]

That's the wrong image to check. It's the last image before this section https://output.circle-artifacts.com/output/job/a2b760da-5862-4658-bf9e-0082d15d00c9/artifacts/0/html/auto_tutorials/epochs/20_visualize_epochs.html#plotting-epochs-as-an-image-map

And it now (correctly) has only 1 colorbar

[larsoner]

Yes indeed, thanks @drammock !