Apply checkstyle to test modules + fix checkstyle issues

[kornys]

Description

Require checkstyle also on all test modules

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• New and existing unit/integration tests pass locally with my changes

[kornys]

@Frawless @im-konge
Quaestion is :)
What is our default indent settings
I have in IDEA
4
4
8

Lukas has I think
4
4
4

not sure what is better
If we decide I can in this PR also change indentation in rest of the files

[im-konge]

As I mentioned before, 4,4,4 is natural for me, the 8 spaces for the continuous lines is a bit weird for me. And I think that it should be same across everything (I mean the 4 spaces).

[kornys]

As I mentioned before, 4,4,4 is natural for me, the 8 spaces for the continuous lines is a bit weird for me. And I think that it should be same across everything (I mean the 4 spaces).

ok then I can require it and change it in my IDEA