[FLINK-40208] Add JobMdcRegistry for config-driven MDC enrichment

[Izeren]

What is the purpose of the change

Add JobMdcRegistry, a process-wide registry that maps JobID to an enriched MDC context derived from job configuration. This enables operators to surface custom job config values (e.g. org ID, environment) in Flink's JVM logs via MDC.

Brief change log

• Add MdcOptions with mdc.job-configuration-to-mdc-keys (Map<String,String>) config option
• Add JobMdcRegistry: static registry populated in Dispatcher and TaskExecutor
• Update MdcUtils.asContextData(JobID) to consult the registry before falling back to the plain job-id singleton
• Add JobIDLoggingITCase.testEnrichedMdcLogging to verify enriched keys appear in log output

Verifying this change

This change added tests and can be verified as follows:

• Added JobMdcRegistryTest covering register, overwrite, unregister, and isolation between jobs
• Extended MdcUtilsTest with parameterized tests for config extraction and registry-first lookup
• Added JobIDLoggingITCase.testEnrichedMdcLogging as an end-to-end integration test

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): yes (MdcOptions is @PublicEvolving)
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? yes
• If yes, how is the feature documented? JavaDocs + config docs auto-generated from ConfigOption

---

Was generative AI tooling used to co-author this PR?

• Yes (Claude Code)

Generated-by: Claude Code

[flinkbot]

CI report:

• ef23cd8 Azure: FAILURE

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run azure re-run the last Azure build