chore(components): harmonize mgt port usage

[squakez]

As it already happens for CSB and Q runtimes

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[gnodet]

Claude Code on behalf of Guillaume Nodet

A few observations on this change:

Behavioral change

This is not just harmonization — it's a behavioral change for existing users. Before this PR, if someone uses camel-observability-services with camel-main (without the k8s export path), the management endpoints bind to port 8080 (the default in HttpManagementServerConfigurationProperties). After this PR, they bind to 9876. This could silently break existing deployments that have health checks, monitoring, or load balancers pointing at 8080.

Migration guide

Since this changes the default port, it should be documented in the upgrade guide (docs/user-manual/modules/ROOT/pages/camel-4x-upgrade-guide-4_19.adoc) so users are aware of the change.

Scattered defaults

The "9876" default is now defined in multiple places:

• KubernetesExport.java:523 — hardcoded "9876" as fallback
• observability-services.properties — this PR
• observability-services.adoc — docs already claim 9876

Meanwhile, HttpManagementServerConfigurationProperties still defaults to 8080. It might be cleaner to change the default at the source (HttpManagementServerConfigurationProperties.port = 9876) or use a shared constant, rather than overriding it per-location. That way all consumers automatically get the right default.

Missing JIRA

Should there be a JIRA issue tracking this change?

[squakez]

No, this is bringing back to the default as expected to 9876 as already documented in version 4.12. We have introduced some regression along the way. Minor change, no Jira required.