[FLINK-40181][ci] Make spotless checking changes since last green build in ci

[snuyanzin]

What is the purpose of the change

The PR makes GHA running spotless against files changed since last successful build rather than for everything
also more details are at diffplug/spotless#511

Brief change log

GHA: check for last green branch and make spotless running for changes since that branch

Verifying this change

GHA

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)

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Was generative AI tooling used to co-author this PR?

• Yes (please specify the tool below)

[flinkbot]

CI report:

• 89ed101 Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

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

[snuyanzin]

example of GHA https://github.com/snuyanzin/flink/actions/runs/29693623019
from my fork

[snuyanzin]

@flinkbot run azure