Remove all leftovers of datatables

We removed the JS library datatables from the base template and all other templates a long time ago. Currently, there are the following leftovers:

• Still included in YARN_INSTALLED_APPS and ANY_JS
• Initialization in main.js

added part::backend prio::1 type::bug labels

created merge request !660 (merged) to address this issue

mentioned in merge request !660 (merged)

changed title from Remove all leftovers from datatables to Remove all leftovers of datatables

marked the checklist item Still included in YARN_INSTALLED_APPS and ANY_JS as completed

marked the checklist item Initialization in main.js as completed

added board::ready label

closed with merge request !660 (merged)

mentioned in commit 05b71717