Bug 32030: Restore destroy of datatables on beforeUnmount

Bug 32030: Restore destroy of datatables on beforeUnmount

Otherwise the DT's headers where duplicated. We must destroy DT when we
unmount the component.

Edit: Hum maybe not!
Looks like the bug still exists if `yarn build_js` is used instead of
`yarn watch_js`!

Signed-off-by: Jonathan Field <jonathan.field@ptfs-europe.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>