[FIX] l10n_ar: remove inconsistent tax demo data

Remove tax demo data:
- They have the same tax name which breaks a uniqueness constraint, and
cause error at migration.
- It doesn't make sense to have taxes demo data
Also remove assignation of those taxes on other aml demo data.

closes odoo/odoo#130773

X-original-commit: 2eeab8fc
Signed-off-by: Laurent Smet (las) <las@odoo.com>
Signed-off-by: Claire Bretton (clbr) <clbr@odoo.com>