denormalize "public" schema to "PUBLIC"

denormalize "public" schema to "PUBLIC"

Fixed reflection bug where Oracle "name normalize" would not work correctly
for reflection of symbols that are in the "PUBLIC" schema, such as
synonyms, meaning the PUBLIC name could not be indicated as lower case on
the Python side for the :paramref:`_schema.Table.schema` argument. Using
uppercase "PUBLIC" would work, but would then lead to awkward SQL queries
including a quoted ``"PUBLIC"`` name as well as indexing the table under
uppercase "PUBLIC", which was inconsistent.

Fixes: #9459
Change-Id: I989bd1e794a5b5ac9aae4f4a8702f14c56cd74c2