[hotfix][build] Use ${flink.shaded.version} for flink-docs and flink-runtime

[snuyanzin]

What is the purpose of the change

This is a trivial PR making using of ${flink.shaded.version} in flink-docs and flink-runtime pom files instead of version.

Brief change log

flink-docs/pom.xml
flink-runtime/pom/xml

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:

• a1376ee Azure: SUCCESS

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