[cmd/mdatagen] add field for configuring individual metric interval

[cuichenli]

Description

Add an Interval field to the individual metric configuration, allowing users to specify custom intervals for each metric. This enables flexibility in cases where different metrics require distinct collection intervals.

Note: Additional changes are needed in the receiver layer to fully support this functionality.

[bogdandrutu]

What does an interval mean for a metric? Most of our scrapers scrape all metrics in one RPC/REST call... How would this be supported?

[cuichenli]

Apologies for the confusion in the description. This is primarily intended for database scrapers. Since these metrics are queried directly from the database and some of them are resource-intensive, it would be beneficial to allow certain metrics to be scraped less frequently.

[bogdandrutu]

We should make the generation of this config optional then.

So, do you mean that in the SQL world, every metric is a sql request?

[cuichenli]

I cannot speak for all databases, but let's take MSSQL and PostgreSQL as examples. In the contrib repository, these metrics are collected by sending SQL queries.

For reference:

PostgreSQL: client.go#L293

MSSQL: queries.go#L14

I will update the code to make this behavior optional

[cuichenli]

updated, please take a look, thanks!

[codecov]

Codecov Report

Attention: Patch coverage is 94.11765% with 3 lines in your changes missing coverage. Please review.

Project coverage is 91.55%. Comparing base (0d2f646) to head (4c6e2db).
Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
...plereceiver/internal/metadata/generated_metrics.go	93.61%	2 Missing and 1 partial ⚠️

❌ Your patch check has failed because the patch coverage (94.11%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #12317   +/-   ##
=======================================
  Coverage   91.55%   91.55%           
=======================================
  Files         467      467           
  Lines       25652    25703   +51     
=======================================
+ Hits        23485    23533   +48     
- Misses       1768     1770    +2     
- Partials      399      400    +1     

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[dmitryax]

@cuichenli please add a changelog entry in https://github.com/open-telemetry/opentelemetry-collector/tree/main/.chloggen

[cuichenli]

@cuichenli please add a changelog entry in main/.chloggen

thanks, updated!