[FLINK-33916][ci] Adds nightly workflow for most-recently published Flink version

[XComp]

Based on the following PR(s):

• https://github.com/apache/flink/pull/23961
• https://github.com/apache/flink/pull/23962
• https://github.com/apache/flink/pull/23965
• https://github.com/apache/flink/pull/24061
• https://github.com/apache/flink/pull/23964
• https://github.com/apache/flink/pull/23970
• https://github.com/apache/flink/pull/23971
• === THIS PR ===

What is the purpose of the change

Creates an extended CI workflow that runs on master

Brief change log

• Adds release-1.18 workflow configuration
• Adds release-1.18 workflow

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

[flinkbot]

CI report:

• c1017395a182d309d15db0e247ccdc06a8ba7eb9 Azure: SUCCESS

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