[receiver/mongodbatlas] Duplicate Metrics

[cpheps]

Describe the bug
For metrics that have several datapoints identified by attributes, like mongodbatlas.process.asserts, the datapoints are spread across duplicate metrics rather than all bundled under a single metric. This is causing an issue specifically in the googlecloudexporter as Stackdriver is detecting these as duplicate metrics, since they all have the same timestamp, and rejecting them.

Steps to reproduce
Configure mongodbatlas receiver with googlecloudexporter and wait a few collections.

What did you expect to see?
No errors during the process with a valid config.

What did you see instead?
Getting export errors like this:

Exporting failed. Try enabling retry_on_failure config option.	{"kind": "exporter", "name": "googlecloud", "error": "[rpc error: code = InvalidArgument desc = One or more TimeSeries could not be written: Field timeSeries[100] had an invalid value: Duplicate TimeSeries encountered.

What version did you use?
Version: v0.45.1

What config did you use?
Config:

receivers:
  mongodbatlas:
    public_key: REDACTED
    private_key: REDACTED

processors:
  batch:

exporters:
  logging:
  googlecloud:
    retry_on_failure:
      enabled: false

service:
  pipelines:
    metrics:
      receivers: [mongodbatlas]
      processors: [batch]
      exporters: [logging, googlecloud]

Environment
OS: MacOS 12.2.1
Compiler(if manually compiled): go 1.17.8

Additional context
This should be an implementation fix only. I also saw this receiver was not using the --experimental-gen flag for mdatagen which would likely make solving this issues easier.

I am happy to volunteer to make these changes if the owner does not want too.

[jpkrohling]

cc @zenmoto

[cpheps]

Can someone assign this to me. I'm assigned to #7145 which I think will solve this issue also.

[jpkrohling]

Assigned, it would still be good to get an ack and review from the code owner for this component (@zenmoto).