[receiver/dockerstats] Combine and simplify multiple blockio metrics by making "operation" an attribute

[jamesmoessis]

Description:

Instead of having several blockio metrics with the operation appended on the name as .read, .write, .sync, .async, .total, .discard we pull the operation out into an attribute. This simplifies the code a lot:

1. Much less generated code, since that scales with amount of metric names.
2. Simplifies the recording logic, as we don't have to map the operation from the stat to a recording function, we put it in an attribute instead.
3. It also makes sense from an otel/metrics perspective, as it more closely aligns with the approach of the semconv (tending towards using attributes instead of additional metric names where possible).

This is a breaking change for anyone using the featuregated v2 implementation, which is not enabled by default yet. To my knowledge, no one is using the new v2 implementation yet.

Link to tracking Issue: #9794

Testing:

The tests logic remain the same, but the expected metrics are updates to align with the changes.

Documentation:

Documentation automatically updated by go generate.

[jamesmoessis]

@rmfitzpatrick @MovieStoreGuy FYI + please review if you have time 😄

[MovieStoreGuy]

This change makes sense to me.

[jamesmoessis]

Hi @rmfitzpatrick @djaglowski just bumping this PR

[rmfitzpatrick]

These changes seem good to me, and I imagine similar updates can be made to the container.network.io.usage metrics w/ direction and ~state attributes, though that may be related to the outcome of open-telemetry/opentelemetry-specification#2726.

[jamesmoessis]

@jpkrohling @djaglowski I have codeowner approval and one other approval. Can I get this reviewed/merged please 😃

[jpkrohling]

approving by proxy