[FLINK-35552][runtime] Moves CheckpointStatsTracker out of DefaultExecutionGraphFactory into Scheduler

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PR Chain

• FLINK-35550: https://github.com/apache/flink/pull/24909
• FLINK-35551: https://github.com/apache/flink/pull/24910
• ⭐ FLINK-35552: https://github.com/apache/flink/pull/24911
• FLINK-35553: https://github.com/apache/flink/pull/24912

What is the purpose of the change

The AdaptiveScheduler needs to have access to the CheckpointsStatsTracker to monitor checkpoint-related events.

Brief change log

• Refactors CheckpointStatsTracker constructor to not rely on the total subtask count anymore when initializing the tracker
• Moves CheckpointStatsTracker ownership from DefaultExecutionGraphFactory to the scheduler implementations
• Makes CheckpointStatsTracker an "implementation detail" of the execution graph that's not exposed through API.

Verifying this change

• Existing tests are covering the change.

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: yes
• 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

[flinkbot]

CI report:

• f52650d9a1586e971d5736a0ac69dc4a06f03bc4 UNKNOWN
• 3764e627199e89cbb72aaaf9bc47e8fee7097704 Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

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

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@flinkbot run azure

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Force-pushed the rebase onto the most-recent version of base PR #24910

$ git rebase --onto=FLINK-35551 6af9560d62f963fc8d85d26807627aa452932fcf

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@flinkbot run azure

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I rebased the branch to master after the base PR #24910 was merged to master.

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Observed CI failures documented:

• FLINK-25453 for the SqlGatewayE2ECase.testMaterializedTableInFullMode
• FLINK-35722 for the CoordinatorEventsToStreamOperatorRecipientExactlyOnceITCase.testCheckpoint

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@flinkbot run azure

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CI with AdaptiveScheduler enabled was successful. I'm gonna go ahead and prepare this PR to be merged (i.e. remove the DO-NOT-MERGE commit).