Operation help goes to wrong page

[dtasev]

Summary

The help for any filter below the first separator (--------) goes to the wrong help page.

This seems to happen in the mantidimaging/gui/windows/operations/view.py::open_help_webpage function, the currentIndex() no longer returns the correct index as we now have separators inside the list.

A crude fix for this was done in #821 but that will be contained only for the release branch.

Steps To Reproduce

• Open Operations window
• Select Divide
• Click the ? for help
• The web page opened will not be for the divide filter

Expected Behaviour

The help page should always be correct

Context

Failure Logs

Screenshot(s)

[samtygier-stfc]

#821 Merged, but keeping bug open for more general fix.