[web] stop looking at a request's Cache-Control header
As per RFC 7234 (HTTP 1.1 Caching):
The "Cache-Control" header field is used to specify directives for
caches along the request/response chain.
CubicWeb is not a cache.
Experiment with the search bar. Try queries like "card sometextualcontent" or
"card wikiid index" or "345".