[chore][elasticsearchreceiver] Add stability level per metric (#42930)

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#### Description

open-telemetry/opentelemetry-collector#13756
added support for exposing metrics' stability level in the generated
documentation. This PR makes use of this functionality.

We start by setting the stability of all metrics to `development`. More
info about levels can be found at
https://github.com/open-telemetry/opentelemetry-specification/blob/v1.49.0/oteps/0232-maturity-of-otel.md#maturity-levels.

Related to:
- open-telemetry/opentelemetry-collector#11878
- open-telemetry/opentelemetry-collector#13297
-
#35325
-
#42809

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Fixes ~

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#### Testing
~

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#### Documentation
Updated

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Signed-off-by: ChrsMark <[email protected]>

Author: ChrsMark