Stop axes labels being hidden by the plot window

[jhaigh0]

Description of work.

This PR fixes the bug where the axes labels of a plot could be hidden outside the edge of the plot window after resizing.

To test:

• Load some data
• Plot a spectrum
• Play around with resizing the window and check that the axes labels remain visible up until matplotlib is forced to push them outside the window (almost minimum window size).
  • When this happens there should be one warning issued for horizontal and vertical limits respectively

It may be worth comparing to another branch to observe how it was problematic before.

Fixes #34049

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[robertapplin]

The axes labels are now visible up until the plot becomes very small. Just had one code question

[martyngigg]

Just so we don't lose track. Is this the PR we need to revert to avoid the plot layout issues. I think we should do this before the beta goes out?

Release 6.6 bug fix issues: #34973 #34974

[martyngigg]

We unfortunately can't just revert this PR as it's on main and it will revert other things like 6.7 release notes too.