Centralize waiting cursor usage

This PR also fixes a bug introduced by this commit https://github.com/geoadmin/mf-geoadmin3/commit/f5f45bbf429b8771fe85cef1307608ff79ff0608

Step to reproduce were:
1) Open app
2) Type ch (and fast after delete c or ch)

Result: waiting cursor is activated

Expected result: waiting cursor is removed

The counter that was previously implemented in the search directive is now in gaWaitCursor.

In this directive, we only remove the waitcursor, never add it. This doesn't break anything, but I think this is inconsistent (It was like this before already).