[FLINK-29397][runtime] Check if changelog provider is null

[zentol]

No description provided.

[flinkbot]

CI report:

• c5c51db Azure: FAILURE

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[pnowojski]

Thanks for the fix @zentol. It will need to be backported to 1.15.x and 1.16.x . It's strange that this issue hasn't been already reported.