[FIX] project: handle limit=None on tags `name_search`

Issue:
After 213b6885, some custom filters
on tags can throw a stacktrace.

Steps to reproduce:
- Install Project
- Project > Custom Filter > Tags contains 'Internal'
- Stacktrace

Cause:
When `limit=None`, which is explicitly set when creating custom
filters, the `name_search` crashes when comparing an `int` (the len
(ids)) with the limit which is `None`.

Fix:
Elaborate the condition to handle the case when `limit=None`.

Affected versions:
16.0 up to master

Reference:
opw-3510309

closes odoo/odoo#135761

Signed-off-by: Audric Onockx (auon) <auon@odoo.com>