[FLINK-29402][state backends] Add RocksDB options for DirectIO reads …

[Donaschmi]

What is the purpose of the change

This pull request adds two configurable RocksDB options enabling the use of DirectIO for reads and background flush and compactions.

Brief change log

• Add state.backend.rocksdb.use-direct-reads to enable DirectIO for read operations
• Add state.backend.rocksdb.use-direct-writes to enable DirectIO for background flush and compactions

Verifying this change

This change is already covered by existing tests, such as testConfigurableOptionsFromConfig.

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? yes
• If yes, how is the feature documented? docs

[flinkbot]

CI report:

• e3e6a19 Azure: FAILURE

Bot commands

The @flinkbot bot supports the following commands:

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

[Donaschmi]

@flinkbot run azure

[klion26]

Since we have already agreed on the issue, let's close this PR here