7f845f7b5e
Since SPR-11792, Last-Modified and ETag headers are also written in
`HTTP 304 Not Modified` responses. This is expected as per
https://tools.ietf.org/html/rfc7232#section-4.1 .
Those tests expected "Last-Modified" to be missing in case of HTTP 304
responses, which is not the case anymore since 953608ec .
Issue: SPR-11792