Speedup search by disabling row-related callbacks while searching.

This does 2 things:

1. Simplifies existing code.
2. Expands the solution applied to set-cursor to other row-related callbacks, leading to massive speedups when deleting the search query in an active search with many results.

To reproduce the slowdown:

1. Open 2 tabs in your Home directory (or root).
2. Make a very generic search query, something like as, in both tabs.
3. Change between the tabs and try to edit the query. Sometimes Thunar will freeze for quite long (more than 10 seconds on a Ryzen 7 4700U with an SSD).

The slowdown still exists, but it is now much more reasonable.