Make the uncacheable behaviour when there are too many cache tags configurable

Problem/Motivation

Some purge modules (e.g. cloudflare, possibly others) hash the cache tags in the header to reduce the size of the response.

This means that even if cache tags simplify can't get the number of tags below the limit, another module could then reduce the size of the cache tags header further.

So I think it would be useful to add a configuration option so that the uncacheable response behaviour can be switched off, the limit would still be used as a threshold for cache tag simplification, just whatever the result of that would be put back on the header.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes