[FLINK-37027][docs] Translate TO_TIMESTAMP_LTZ descriptions

[amwufiv]

What is the purpose of the change

This pull request translates the Chinese SQL function
documentation for the TO_TIMESTAMP_LTZ overloads added in
FLINK-36862.

Brief change log

• Translated the TO_TIMESTAMP_LTZ(numeric[, precision])
  description in docs/data/sql_functions_zh.yml.
• Translated the TO_TIMESTAMP_LTZ(string1[, string2[, string3]]) description in docs/data/sql_functions_zh.yml.

Verifying this change

This change is a documentation-only update.

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

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

• Yes (please specify the tool below)‘

Generated-by: Codex

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CI report:

• 150f615 Azure: FAILURE

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