[metricbuilder] proposing adding NewMetricData

[codeboten]

Description:
Many metric scrapers are setting the instrumentation name after initializing pdata. This change proposes adding a generated function that could be used more generically instead. It pulls the instrumentation name from the metadata for consistency.

Note this PR is updating the code in a few scrapers to show what the change looks like. I'm happy to split that out of this PR if folks are interested in moving forward with this proposal.

Testing: unit tests

[djaglowski]

I think this is a great idea and looks good.

Just one comment on a complementary change.

[djaglowski]

LGTM, though we should have a changelog entry for the changes to the instrumentation library names.

[codeboten]

@djaglowski i added a note to the changelog. Any thoughts on whether the right thing to do is to name receivers: otel/redisreceiver or to update the name in metadata to redis to end up with the same name we have now otel/redis?

Additionally, the scrapers for various host metrics end up with otel/cpu whereas i think the better name would be otel/hostmetrics/cpu. I'm open to suggestions here.

[djaglowski]

@codeboten, I don't feel strongly about it either way, but the more verbose otelcol/redisreceiver,otelcol/hostmetrics/cpu seem slightly clearer to me.

[dmitryax]

I agree with @djaglowski. otelcol/hostmetrics/cpu looks better to me

[codeboten]

@dmitryax @djaglowski for consistency the hostmetrics scrapers are now identified with: otelcol/hostmetricsreceiver/cpu

I'll follow this PR with another for different components to use NewMetricData. I can tackle the work to remove it shortly after

[dmitryax]

LGTM