docs: clarify OTLPMetricsWriter unavailability on Debian 11 and Ubunt…

[00Manas-Singh00]

• Add prominent note in OTLP feature docs with root cause:
• package builds disable OpenTelemetry (ICINGA2_WITH_OPENTELEMETRY=OFF) due to older default Protobuf toolchain.
• Add the same caveat to the OTLPMetricsWriter object type reference.
• Add install-time note in Debian/Ubuntu installation section.
• Add upgrade-path caveat in ElasticsearchWriter -> OTLPMetricsWriter migration section.
• Include verification command and practical alternatives (build with newer Protobuf toolchain or use newer distro release).

Fixes #10823.

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[bobapple]

@cla-bot check

[oxzi]

FTR, this would close #10823.

[00Manas-Singh00]

I have removed the proposed lines from installation and features docs. Let me know if there are any more changes to be made

[oxzi]

Thanks.

Next to the one comment, please add yourself to the AUTHORS file at the alphabetically correct position.

[oxzi]

Sorry for this second change request, but please also mention the absence for Amazon Linux 2, as now updated in the original issue #10823. Thanks again!

[00Manas-Singh00]

@oxzi I have removed the newline, mentioned the absence for Amazon Linux 2 as per issue #10823 and added myself to the authors as mentioned by you. Thanks!

[oxzi]

LGTM, thanks!

[oxzi]

CI is blocked until either #10832 is merged or it unblocks itself 🙃

[00Manas-Singh00]

Hell naww....XD

[oxzi]

After #10832 got merged, I have rebased your branch and restarted the CI.

[backbot-ci]

Successfully created backport PR for support/2.16:

• [Backport support/2.16] docs: clarify OTLPMetricsWriter unavailability on Debian 11 and Ubunt… #10837