[GOBBLIN-2202] Change aggregation temporality to DELTA instead of CUMULATIVE for Open Telemetry Metrics

[Blazer-007]

Dear Gobblin maintainers,

Please accept this PR. I understand that it will not be reviewed until I have checked off all the steps below!

JIRA

• My PR addresses the following Gobblin JIRA issues and references them in the PR title. For example, "[GOBBLIN-XXX] My Gobblin PR"
  • https://issues.apache.org/jira/browse/GOBBLIN-2202

Description

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  Changed Aggregation Temporality to DELTA instead of CUMULATIVE for Open Telemetry Metrics

Tests

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  NA

Commits

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  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

[abhishekmjain]

Will this impact consumers of the metrics working with CUMULATIVE?

[Blazer-007]

Will this impact consumers of the metrics working with CUMULATIVE?

Yes this will impact the users who are working with OTel collector which supports only Cumulative .
Microsoft MDM doesn't support Cumulative specially for monotonic metrics that's why the change is required

[Blazer-007]

More about temporality here - https://opentelemetry.io/docs/specs/otel/metrics/data-model/#temporality

[vsinghal85]

Do we know why metrics were not being emitted using CUMULATIVE? In case if for some usecase we want to use CUMULATIVE, would that be something possible, or is there some blocker which prevents that?