feat(metrics): move to otel abstractions for metrics recording

[GeorgeMac]

This updates the three existing packages which record prom metrics.
It updates them to record their metrics via the otel abstractions.

The packages are:

• server
• cache
• storage (database/sql)

The result is some slight adjustments to how the metrics are named.
Most notable is the database stats ones.
Because it turns out, otelsql package we use for tracing has all the instruments for metrics too.
Using this package changes the names to be db_sql_connection_ and db_sql_latency_ prefixed.
They make some good choices regarding metric types. Even rolling latency up into a histogram.

[codecov-commenter]

Codecov Report

Merging #1147 (e13fdbf) into main (5264927) will increase coverage by 0.60%.
The diff coverage is 76.47%.

❗ Current head e13fdbf differs from pull request most recent head 5eaa1e7. Consider uploading reports for the commit 5eaa1e7 to get more accurate results

@@            Coverage Diff             @@
##             main    #1147      +/-   ##
==========================================
+ Coverage   79.31%   79.91%   +0.60%     
==========================================
  Files          36       35       -1     
  Lines        2562     2435     -127     
==========================================
- Hits         2032     1946      -86     
+ Misses        434      393      -41     
  Partials       96       96              

Impacted Files	Coverage Δ
internal/server/cache/redis/cache.go	63.63% <42.85%> (-11.98%)	⬇️
internal/server/cache/memory/cache.go	100.00% <100.00%> (ø)
internal/server/middleware.go	61.21% <100.00%> (ø)
internal/storage/sql/db.go	90.90% <100.00%> (+0.21%)	⬆️

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[markphelps]

lgtm, would you mind adding a section to the CHANGELOG under ##unreleased about the metric renaming so that we don't forget at release time?

[markphelps]

i like this pattern much better than what we were previously having to do