Clarify that stats refers to statistics

[AdrianPotter]

Description of work

Title the statsPanel Beam statistics to make it slightly clearer. Having thought about what I commented eariler Beam information is too generic. I also modified the code documentation slightly to make it clearer what Stats means. One other minor change was to remove an unused variable.

To test

ISISComputingGroup/IBEX#1596

Acceptance criteria

Clear in GUI what the bottom right panel in the beam status perspective is

---

Code Review

• Is the code of an acceptable quality?
• Does the code conform to the coding standards? Is it well structured with small focussed classes/methods/functions?
• Are there unit tests in place? Are the unit tests small and test the a class in isolation?
• Are there system tests in place? Do they test a minimal set of functionality and leave the gui as close as possible to its original state?
• Did any existing system test break as a result of the current changes?
• Have the changes been documented in the release notes. If so, do they describe the changes appropriately?
• Has the manual system tests spreadsheet been updated?

Functional Tests

• Do changes function as described? Add comments below that describe the tests performed.
• How do the changes handle unexpected situations, e.g. bad input?
• Has developer documentation been updated if required?

Final Steps

• Reviewer has moved the release notes entry for this ticket in the "Changes merged into master" section