Remove OLD_FILE_NAMING code. No longer used.

src/backend/catalog/catalog.c

src/backend/catalog/index.c

src/backend/commands/indexcmds.c

src/backend/tcop/utility.c

src/backend/utils/init/postinit.c

src/backend/utils/misc/database.c

src/include/catalog/catalog.h

src/include/catalog/index.h

src/interfaces/odbc/connection.h