Bug 25485: TinyMCE broken in Debian package installs

Bug 25485: TinyMCE broken in Debian package installs

When installing the Debian package of Koha, we install the Debian tinymce package and symlink over our own tinymce libs that are in the Koha codebase. This version of tinymce does not have the same files and because of this, tinymce does not get loaded.

We should remove the use of the tinymce Debian package, and just use our own version of TinyMCE.

Test Plan:
1) Install Koha 19.11 from package
2) Browse to the news editor
4) Note the WYSIWYG editor is missing
5) Build a new Koha package with this patch applied, install it
6) Reload the news editor
7) Note the WYSIWYG editor is back!

Signed-off-by: David Cook <dcook@prosentient.com.au>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>