[Python][C++] index_in_meta_binary/is_in_meta_binary should not show up in functions list

[asfimport]

The index_in_meta_binary function is an implementation detail and should not show up in the list of functions.

The same also applies to is_in_meta_binary

Reporter: Weston Pace / @westonpace

Related issues:

• [Python] Hide hash_* functions from pyarrow.compute (is related to)
• [C++] Duplicate functions array_filter/array_take and filter/take (is related to)

_{Note: This issue was originally created as ARROW-13949. Please see the migration documentation for further details.}