[FLINK-26805][table] Managed table breaks legacy connector without 'connector.type'

[JingsongLi]

What is the purpose of the change

Fix the bug, Managed table breaks:

CREATE TABLE T (a INT) WITH ('type'='legacy');
INSERT INTO T VALUES (1); 

This case can be misinterpreted as a managed table, which the user might expect to be resolved by the legacy table factory.

Brief change log

• Move isLegacyConnectorOptions to TableFactoryUtil.
• ManagedTableListener.isManagedTable should exclude legacy connector.

Verifying this change

• LegacyTableFactoryTest.

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

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)

[flinkbot]

CI report:

• 43760bc Azure: SUCCESS

Bot commands

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

[wuchong]

LGTM.