[FLINK-33474][runtime-web] fix undefined error of show plan in job su…

[yuchen-ecnu]

…bmit page

What is the purpose of the change

Fix the undefined exception of Plan Visualization in the Job Submit Page on Flink WEB.

Brief change log

• Before calling flush of dagreComponent, call cdr.detectChanges() first to make sure dagreComponent loaded

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

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): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable

[yuchen-ecnu]

Hi @Myasuka, would you like to help review this PR?

[flinkbot]

CI report:

• 27454f1 Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

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

[Myasuka]

LGTM.