[consumer] Fix comments referencing MetricsData

[mx-psi]

Description:

• Fix comments introduced in Move the metrics definition to pdata. Remove internal/data definition #1720 that kept the old name (MetricsData) instead of the new one (Metrics)

Link to tracking Issue: n/a

Testing: n/a this is a docs change

Documentation: Updated strings that used the old name.

[codecov]

Codecov Report

Merging #2378 (aa689df) into master (6f772bf) will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2378      +/-   ##
==========================================
+ Coverage   92.01%   92.04%   +0.02%     
==========================================
  Files         273      273              
  Lines       15434    15426       -8     
==========================================
- Hits        14202    14199       -3     
+ Misses        850      847       -3     
+ Partials      382      380       -2     

Impacted Files	Coverage Δ
consumer/pdata/metric.go	99.27% <ø> (ø)
internal/data/bytesid.go	76.92% <0.00%> (-4.03%)	⬇️
exporter/otlpexporter/otlp.go	74.35% <0.00%> (+2.56%)	⬆️
exporter/exporterhelper/metricshelper.go	100.00% <0.00%> (+5.40%)	⬆️

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