Last modified filter dropdown doesn't need text filter

[kulmann]

Describe the bug

The last modified date range filter dropdown on the search result page shows a text filter at the top to narrow down filter items in the dropdown. Since there are only a few items now and owncloud/ocis#7919 will reduce it even further, we don't need the filter. Should be disabled.

Steps to reproduce

1. Use global search with search term "test"
2. Click on the last modified filter chip

Expected behavior

Super easy to understand UI

Actual behavior

There is an unnecessary text filter in the dropdown

Screenshots