remove the variables section from the radio button and checkbox type
minor #3677 [Reference][Forms] Remove variables section from tables (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
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[Reference][Forms] Remove variables section from tables

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

Commits
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490633b remove the variables section from the radio button and checkbox type