Fix caching headers, drop HTTP/1.0 support

What does this MR do and why?

We've discovered that default_cache_headers sets Pragma: no-cache for HTTP/1.0 compatibility, which breaks caching in the application. For example, if you set expires_in 1.minute it translates to Cache-Control: max-age=60, private, but if you also set Pragma: no-cache, browser just ignores it and still makes the request.

In this MR we are removing all Pragma: no-cache references. I do not believe this is a breaking change since we rewrite HTTP/1.0 requests into HTTP/1.1. That means that we already do not follow HTTP/1.0 specification and are going to reflect that in our code.

The proposal issue: #391874 (closed)

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Related to #391874 (closed)