[FLINK-30478] [core] Avoiding dependence on JDK-internal code

[sdmoralesma]

What is the purpose of the change

Increasing the usability of Flink with JDK 17: sun.net.util.IPAddressUtil is not exported by the JDK, i.e. --add-opens configuration is needed for making use of it.

Brief change log

• Replace usage of sun.net.util.IPAddressUtil with com.google.common.net.InetAddresses in production and testing code.
• Complement coverage of unit test case when host is null.

Verifying this change

This change is already covered by existing tests, such as NetUtilsTest and TaskManagerRunnerConfigurationTest.

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:

• 26a4c5f Azure: SUCCESS

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