tiflow: add MariaDB source for DM integration test

[joechenrh]

Summary\n- add MariaDB service wiring for TiFlow DM integration test pod\n- include MariaDB-backed case in latest DM integration pipeline\n\n## Notes\n- this PR is opened as draft and should be merged after the DM-side branch lands.

[ti-chi-bot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign purelind for approval. For more information see the Code Review Process.
Please ensure that each of them provides their approval before proceeding.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• pipelines/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[gemini-code-assist]

Code Review

This pull request adds a MariaDB sidecar to the DM integration test pipeline, updating the Kubernetes pod configuration and the Jenkins pipeline to include health checks and environment variables. Feedback focuses on reducing the sidecar's resource limits to prevent scheduling issues and moving hardcoded arguments to environment variables to comply with Prow job standards and avoid GTID collisions.

[gemini-code-assist]

The resource limits for the MariaDB sidecar are quite high (2 CPUs and 4Gi memory). Since this Pod already contains multiple database sidecars, these high limits (which default to requests in many Kubernetes configurations) significantly increase the Pod's total resource footprint. This could lead to scheduling delays or failures if the total Pod requests exceed the capacity of the CI nodes. Consider reducing these to more modest values, such as 500m CPU and 1Gi memory, which are typically sufficient for integration test workloads.

          memory: 1Gi
          cpu: 500m

[gemini-code-assist]

Using server-id=1 for all database sources is not recommended as it can lead to GTID set collisions in MariaDB. Additionally, per repository rules for Prow job definitions, test parameters should be configured via environment variables in the container's env field rather than being hardcoded directly in command arguments. Please move this configuration to the env section and reference it here.

        - "--server-id=$(MARIADB_SERVER_ID)"

References

1. In Prow job definitions, use environment variables in the container's env field to configure test parameters like concurrency, CPU, and memory, rather than hardcoding them in command arguments.