Nuke < and > in query strings

Those characters mean "token range" in Elasticsearch.  So "<cow" finds
all tokens before cow.  "<=cow" is before and equal to.  > does what you
expect.  Neither are really expected by our users.

Oddly, / doesn't properly escape them from the query string like it does
everything else.  Oh well.  We just remove them.

Bug: 60496
Change-Id: I941ee79e00760f42ff4d3ca7b240e8209649ad63
Merge "Nuke < and > in query strings"