Fix outdated Zeebe env var names in broker config docs after 8.9 rename (provide mapping table)

[deng-leon]

There is a mismatch between the Zeebe broker config environment variable documentation and the 8.9 property reference.

Affected pages:

• Zeebe Broker Config - Command API
• Core Settings: Properties

In Camunda 8.9, the environment variables for broker/cluster settings were renamed from ZEEBE_BROKER_... to CAMUNDA_CLUSTER_... (see this task). However, the documentation pages above still reference a mix of old and new variable names and have different capitalization and word separation styles. This can cause confusion or misconfiguration for users.

Overview of environment variable naming mismatch (examples):

Property / Setting	Old variable (pre-8.9, shown in Broker Config)	New variable (8.9+, in Property Reference)
Network command API host	ZEEBE_BROKER_NETWORK_COMMANDAPI_HOST	CAMUNDA_CLUSTER_NETWORK_COMMANDAPI_HOST
Network command API port	ZEEBE_BROKER_NETWORK_COMMANDAPI_PORT	CAMUNDA_CLUSTER_NETWORK_COMMANDAPI_PORT
Network command API advertised host	ZEEBE_BROKER_NETWORK_COMMANDAPI_ADVERTISEDHOST	CAMUNDA_CLUSTER_NETWORK_COMMANDAPI_ADVERTISEDHOST
Network base host	ZEEBE_BROKER_NETWORK_HOST	CAMUNDA_CLUSTER_NETWORK_HOST
Network advertised host	ZEEBE_BROKER_NETWORK_ADVERTISEDHOST	CAMUNDA_CLUSTER_NETWORK_ADVERTISEDHOST
Network port offset	ZEEBE_BROKER_NETWORK_PORTOFFSET	CAMUNDA_CLUSTER_NETWORK_PORTOFFSET
...	...	...

Note: The old and new patterns follow the same segment structure but differ in their prefix and sometimes capitalization/word splitting.

Proposed fix:

• Update the Zeebe broker config page to reference (and explain) only the new CAMUNDA_CLUSTER_... environment variable names as introduced in 8.9.
• Ensure all examples, tables, and explanatory text use the new convention.
• Consider adding a brief mapping or migration section to help users with legacy configs.
• Normalize the presentation/capitalization of environment variable names and property names, and clarify their mapping if needed.

Background:

• In Camunda 8.9, the env variable scheme for Zeebe was renamed from zeebe_broker_.../ZEEBE_BROKER_... to camunda_cluster_.../CAMUNDA_CLUSTER_....
• Affected users may reference the wrong environment vars if following the old docs.