Script Generator: Fix scaling issue with buttons

[GRyall]

Issue Description

As an instrument scientist I would like the run pause and stop buttons, along with radial button and checkbox options in the same area, to not scale to zero size when I reduce the size of my window.

How & Where?

The following screenshots show the issue on EMU (who initially reported it)

Before scaling:

After the window is too small, notice buttons to the right:

Reproducible (Yes)?

Open the script generator view. vary its vertical size.

Additional Information

Once complete, we should patch this on to Muon instruments, where this was reported.

_{See our Git Workflow.}

Acceptance Criteria

• Varying screen height in the script generator view of the GUI does not shrink the buttons mentioned

How to Review

_{Before making a PR...}

• Provide verbose instructions for the reviewer to test that your changes work and fix the issue
• Describe if/how you have implemented testing for this issue
• Provide screenshots of the feature to help the reviewer if relevant

_{If not applicable, write "Not applicable"}

...

_{To the reviewer: Make sure to update submodules!}