CAMEL-23577: docs - add "potential breaking change" suffix to 9 header-rename sub-task entries in the 4.21 upgrade guide

[oscerd]

Summary

Aligns nine CAMEL-23577 sub-task upgrade-guide entries with the convention
established for the camel-jira entry (and used for camel-grok,
camel-jgroups, camel-dns, camel-milo): the heading is suffixed with
- potential breaking change to make it obvious to readers scanning the
upgrade guide that the section describes a header-value rename that may break
routes which set the header by its literal string value.

The 9 originally-merged entries (#23435 web3j · #23438 openstack · #23437 pdf
· #23442 elasticsearch+opensearch · #23454 github2 · #23467 google×5 · #23469
arangodb · #23470 jt400 · #23478 mail) shipped with a plain heading by
oversight; this PR adds the same - potential breaking change suffix that
camel-milo (#23474) shipped with on the same day.

Diff

Pure heading-line edit — no section body content changes:

Before	After
=== camel-web3j	=== camel-web3j - potential breaking change
=== camel-openstack	=== camel-openstack - potential breaking change
=== camel-pdf	=== camel-pdf - potential breaking change
=== camel-elasticsearch / camel-opensearch	=== camel-elasticsearch / camel-opensearch - potential breaking change
=== camel-github2	=== camel-github2 - potential breaking change
=== camel-google-functions / camel-google-secret-manager / camel-google-vision / camel-google-text-to-speech / camel-google-speech-to-text	(same, suffixed)
=== camel-arangodb	=== camel-arangodb - potential breaking change
=== camel-jt400	=== camel-jt400 - potential breaking change
=== camel-mail	=== camel-mail - potential breaking change

Total diff: 9 insertions, 9 deletions, one file.

Precedent

Same pattern as the camel-jgroups (#23451) and camel-jira (#23475) follow-up
doc PRs.

Test plan

• git diff --stat shows only the 4.21 upgrade guide modified
• Every -/+ line in the diff is a heading line (verified grep of ^[-+][^-+])
• grep -c "potential breaking change" count goes from 5 → 14 (5 pre-existing + 9 newly added)
• camel-milo heading is already suffixed and is not touched by this PR

Tracker: CAMEL-23577

Reported by Claude Code on behalf of Andrea Cosentino

[github-actions]

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[github-actions]

🧪 CI tested the following changed modules:

• docs

---

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[gnodet]

Docs-only consistency fix adding the - potential breaking change suffix to 9 header-rename sub-task entries in the 4.21 upgrade guide that were missing it. Aligns with the pattern already used for other header rename entries.

LGTM.

Claude Code on behalf of Guillaume Nodet