[RAC] - T Grid always show the leading checkboxes

[fkanout]

Summery

T Grid provides the possibility to hide the leading checkBoxes in the table, and it is configurable via a prop showCheckBoxes with a boolean value. However, this value is hardcoded with true, which means the checkboxes always appear whatever value is passed.

kibana/x-pack/plugins/timelines/public/components/t_grid/standalone/index.tsx

Line 320 in f7d7a34

showCheckboxes: true,

Hiding leading checkboxes required in this issue, so I tried to fix it with showCheckboxes: leadingControlColumns[0].showCheckboxes ?? true,
That fulfilled my requirement, but, unfortunately, it made other tests for other components fail.

AC

• Remove the hard-coded value true and make showCheckBoxes prop configurable.
• Update/Fix the related tests

[kqualters-elastic]

I would suggest solving this like this
no_checkboxes.patch.txt
this way the prop is exposed to use with false, but defaults to true unless specified so that existing tests pass