fix(api): deprecate MetricAttributes and MetricAttributeValue

[blumamir]

Just a small fix to the metrics API comment I spotted when reviewing open-telemetry/opentelemetry-js-contrib#1281

Probably it's a missed copy-paste mistake

deprecate MetricAttribute and MetricAttributeValue to align with SpanAttributes and SpanAttributeValue.

I wonder if it should also be replaced in the api package where it is used (I think yes)

[blumamir]

Should this be added to changelog? feels to me it will just be noise

[codecov]

Codecov Report

Merging #3406 (789fbbf) into main (bd56547) will decrease coverage by 0.01%.
The diff coverage is n/a.

❗ Current head 789fbbf differs from pull request most recent head 041f2a0. Consider uploading reports for the commit 041f2a0 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3406      +/-   ##
==========================================
- Coverage   93.27%   93.26%   -0.02%     
==========================================
  Files         247      247              
  Lines        7348     7348              
  Branches     1512     1512              
==========================================
- Hits         6854     6853       -1     
- Misses        494      495       +1     

Impacted Files	Coverage Δ
api/src/metrics/Metric.ts	100.00% <ø> (ø)
...emetry-core/src/platform/node/RandomIdGenerator.ts	87.50% <0.00%> (-6.25%)	⬇️

[blumamir]

Actually, now I see that for trace API those types are deprecated.
I think it should be aligned in metrics too, right?

/**
 * @deprecated please use {@link Attributes}
 */
export type SpanAttributes = Attributes;

/**
 * @deprecated please use {@link AttributeValue}
 */
export type SpanAttributeValue = AttributeValue;

[legendecas]

We'll need to move away from either SpanAttributes or MetricAttributes in the API package and encourage implementations that depend on the newer API package to use the Attributes instead. These types are identical so there should be no breaking changes.

E.g.

1. https:/open-telemetry/opentelemetry-js/blob/main/api/src/trace/span.ts#L53
2. https:/open-telemetry/opentelemetry-js/blob/main/api/src/metrics/Metric.ts#L65

[legendecas]

We can migrate to Attributes in all occurrences in the API package in a follow-up PR.