Sort by can't be changed from Relevance in text search

[rosanna-smith]

If this should go in auto-ldaca-data-portals let me know and I'll move it.

In Basic and Advanced text search, the Sort by option can't be changed from Relevance to Collection or Name when the results are displayed. If it's expected that only Relevance is allowed in this case, could we change the interface so that the dropdown isn't available?