feat: add label_name_underscore_sanitization and label_name_preserve_multiple_underscores to OTLPConfig

[dongjiang1989]

Description

Describe the big picture of your changes here to communicate to the maintainers why we should accept this pull request.

ref: prometheus/prometheus#17345

• Add labelNameUnderscoreSanitization and labelNamePreserveMultipleUnderscores fields to the OTLPConfig type in the Prometheus CRD.
• Both fields require Prometheus >= v3.8.0 and are only relevant when translation_strategy uses underscore escaping (UnderscoreEscapingWithSuffixes or
  UnderscoreEscapingWithoutSuffixes).
• labelNameUnderscoreSanitization controls whether to prepend key_ to labels starting with _ (reserved labels starting with __ are not modified).
• labelNamePreserveMultipleUnderscores enables preserving multiple consecutive underscores in label names during sanitization (defaults to true).

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Type of change

What type of changes does your code introduce to the Prometheus operator? Put an x in the box that apply.

• CHANGE (fix or feature that would cause existing functionality to not work as expected)
• FEATURE (non-breaking change which adds functionality)
• BUGFIX (non-breaking change which fixes an issue)
• ENHANCEMENT (non-breaking change which improves existing functionality)
• NONE (if none of the other choices apply. Example, tooling, build system, CI, docs, etc.)

Verification

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Changelog entry

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add `label_name_underscore_sanitization` and `label_name_preserve_multiple_underscores` to OTLPConfig