Deprecate int64 as return type of array_length and cardinality

[xiangjinwu]

The 2 functions return integer (int32) in PostgreSQL, but when they were first introduced in RisingWave, the return type was mistakenly implemented as bigint (int64).

This has been fixed by #10267 and new queries will generate plans with correct type. But we also allow old plans with int64 to execute right now.

We have several options:

• (current) Both cardinality(list) -> int32 and cardinality(list) -> int64 are considered valid function overloads. The frontend uses infer_type_for_special to select the int32 version. Note that most array functions require infer_type_for_special anyways except for array_to_string/array-length (singly-typed)/cardinality (singly-typed).
• Reject plans containing cardinality(list) -> int64 after we are confident it is not being used, possibly after we have a tool for users to transform an old-verson query plan to a new-version query plan.
• Move the special handling code to when the executor build exprs. When it sees cardinality(list) -> int64 just build cast(cardinality(list) -> int32) -> int64. Note this cannot use the build_function macro which still inserts cardinality(list) -> int64 as a valid signature.

[xiangjinwu]

maintenance cost is low with #11189, considering it done.