Remove inputs for unsupported properties

Problem/Motivation

These settings are removed or ignored in Fullcalendar v7 but still appear in the Views UI form, where they mislead site builders.

Remove handleWindowResize and windowResizeDelay from form — v7 removed both options; the calendar now auto-resizes automatically. Both fields are currently in the Calendar Appearance fieldset (FullCalendar.php lines 1137–1163).

Remove buttonIcons from form — v7 removed the buttonIcons option. Toolbar icons are now SVG-based and built into each theme. The form field remains in the Toolbar group (FullCalendar.php line 1362). The fcAddEvent button's iconClass pattern is the correct v7 approach and can serve as the documented model for custom icon use.

Remove titleRangeSeparator from form — Already marked deprecated in the field description ("has no effect"), but still visible in the Toolbar group. The field should be removed from the form. Displaying a setting that explicitly does nothing undermines trust in the surrounding options.

Proposed resolution

The form fields should be removed; schema entries can be retained for one release cycle for backwards compatibility with existing exported config, but should be marked as deprecated in the schema.