fix regression of result cache unable to parse cached results

[yeya24]

What this PR does:

This PR fixes a regression introduced in #6180.

ts=2024-09-05T06:02:52.857844346Z caller=handler.go:409 level=error  msg="query stats" component=query-frontend method=GET path=/prometheus/api/v1/query_range error="any: message type \"queryrange.PrometheusResponse\" isn't linked in" param_stats=all param_step=60 param_end=2024-09-04T06:08:00Z param_start=2024-09-04T06:02:00Z param_query=some_query

any: message type \"queryrange.PrometheusResponse\" isn't linked in error came from https://github.com/cortexproject/cortex/blob/v1.18.0/pkg/querier/tripperware/queryrange/results_cache.go#L733. When serializing query response into cacheable content the protobuf type name is encoded. So when fetching cached response back and deserializing it again it requires us to have the queryrange.PrometheusResponse type so it knows how to unmarshal it.

The type was removed in the above PR. To fix this issue, we have to introduce queryrange.PrometheusResponse type back for compatibility purpose. The cache should be able to handle different cached result types and always convert result type to the new one when forwarding the response to downstream.

Besides, I also ensure that we always write old response format to cache for backward compatiblity. So things don't break when there is a rollback and old image cannot parse the cached results.
The idea is to introduce a flag later so that users can migrate with a 2 phase deployment.

Which issue(s) this PR fixes:
Fixes #

Omit the changelog as the regression was not released yet.

Checklist

• Tests updated
• Documentation added
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[CharlieTLe]

Thanks @yeya24! Could you please update the change log as well?

[yeya24]

I think changelog is not needed in this case as the issue was introduced in master and has not been released.

[yeya24]

Will merge as it is