[FLINK-29446][Table SQL/API] Remove Calcite classes since they were fixed in 1.24

[snuyanzin]

What is the purpose of the change

SqlDotOperator, SqlItemOperator, AliasNamespace were introduced as copies from Calcite and with a fix inside at #12649
At the same side the fixed was applied in Calcite itself in 1.24. https://issues.apache.org/jira/browse/CALCITE-4085

Since now Flink depends on 1.26 the fix is included and there is no need to have these classes in Flink repo

Brief change log

• flink-table/flink-table-planner/src/main/java/org/apache/calcite/sql/fun/SqlDotOperator.java
• flink-table/flink-table-planner/src/main/java/org/apache/calcite/sql/fun/SqlItemOperator.java
• flink-table/flink-table-planner/src/main/java/org/apache/calcite/sql/validate/AliasNamespace.java

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:

• 1f7fe4f Azure: SUCCESS

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[snuyanzin]

@twalthr could you please have a look once you have time?
It looks like for some reason these classes were not removed during update to 1.24+

[twalthr]

Thanks @snuyanzin! LGTM.