Solr empty text is awkward for Commons events, includes search keywords field

When no events have been created on the site and Commons Solr is enabled, we see this empty text:

Check if your spelling is correct, or try removing filters.
Remove quotes around phrases to match each word individually: "blue drop" will match less than blue drop.
You can require or exclude terms using + and -: big +blue drop will require a match on blue while big blue -drop will exclude results that contain drop.

as well as a search field.

The interactive prototype indicates that there should be no search keyword form here. Let's also make the empty text something simpler and less search-related.