Add prometheus type field to EMF exporter for CloudWatch compatibility

[bjrara]

Why do we need it?
Currently in CloudWatch agent, a field prom_metric_type will be added to CloudWatch log per item when metrics are collected from Prometheus. In order to keep the behavior the same as CloudWatch agent after user migrating to otel collector, we need to add the same field in EMF exporter.

[codecov]

Codecov Report

Merging #2689 (74fd49a) into main (f8c550f) will increase coverage by 1.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2689      +/-   ##
==========================================
+ Coverage   90.53%   91.60%   +1.06%     
==========================================
  Files         444      445       +1     
  Lines       21984    22073      +89     
==========================================
+ Hits        19904    20220     +316     
+ Misses       1618     1384     -234     
- Partials      462      469       +7     

Flag	Coverage Δ
integration	69.18% <ø> (?)
unit	90.53% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
exporter/awsemfexporter/metric_translator.go	97.91% <100.00%> (+0.20%)	⬆️
processor/groupbytraceprocessor/event.go	95.96% <0.00%> (-0.81%)	⬇️
internal/common/testing/container/container.go	73.68% <0.00%> (ø)
receiver/jmxreceiver/receiver.go	94.80% <0.00%> (+16.88%)	⬆️
receiver/dockerstatsreceiver/docker.go	92.30% <0.00%> (+39.05%)	⬆️
receiver/dockerstatsreceiver/receiver.go	96.72% <0.00%> (+47.54%)	⬆️
receiver/jmxreceiver/subprocess/subprocess.go	96.55% <0.00%> (+74.48%)	⬆️
receiver/redisreceiver/receiver.go	87.50% <0.00%> (+87.50%)	⬆️
receiver/redisreceiver/client.go	100.00% <0.00%> (+100.00%)	⬆️
receiver/redisreceiver/factory.go	100.00% <0.00%> (+100.00%)	⬆️
... and 1 more

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[mxiamxia]

Thanks!

[mxiamxia]

@jrcamp , I carefully reviewed this PR and LGTM. Could you please help to review it?

[mxiamxia]

Hi @bogdandrutu , could you please help on this PR? Thanks!

[anuraaga]

@mxiamxia I see a pattern of combining refactoring and logic changes into single PRs for this component. Can you help to make sure such changes are separated?

[anuraaga]

Ah sorry I got confused it looks like this PR contains #2512 - so it means that's a dependency right?

[bjrara]

@anuraaga Sorry about the confusion. I thought review in tandem would make it easier. Re-org the commit. Hope it help.