fix(metrics): remove Redis spans from Queries insights module

[mjq]

Redis spans were intended to be filtered out of the Queries insights module, since it currently only supports SQL. This used to work via a check for *redis* in the span op. With the JS SDK's v8 release the span op for redis spans became simply db and Redis spans starting showing up in the Queries module.

JS v8 follows the OTel standard of setting the db.system attribute to "redis", so we can use that as a secondary check to bring back the expected filtering.

[gggritso]

The strange thing is, I don't think db.redis was ever omitted from tag extraction, the only check for *redis* is when extracting the span.description tag! I think what's been happening is that we're extracting tags for db.redis but none of them have a span.description tag, so they don't show up in the module. In the V8 SDK the op is "db" which means the spans get metrics buckets and a span.description tag, so they show up in the UI all of a sudden.

The Cardinality Analyzer actually confirms this, there are metric buckets with the "db.redis" op. If true, we should ... probably stop extracting those, by adding "*redis*" to DISABLED_DATABASES?

[jjbayer]

The PR makes sense to me, see also #3642.

+1 on what @gggritso said, db.redis should be in disabled databases.

@mjq could you add a test case to https://github.com/getsentry/relay/blob/master/relay-server/src/metrics_extraction/event.rs to confirm the new behavior?