Hide Materialfilter PeriodOnly in ContentNode

[manuelmeister]

When editing the material for the whole camp, we have a filter on the datatable:

period-filter-useful.mp4

This filter can be useful, and we'd like to keep it.

However, when editing a single activity, the filter is also displayed in the material section:

period-filter-not-needed.mp4

In this context, displaying period materials does not work and indeed is not a useful interaction. The periodOnly filter should be removed in this view. Note: We still need the delete buttons for all of the material items, but the filter option on this column header should be removed.