grn_db_wal_recover: don't remove WAL for temporary objects
grn_db_wal_recover: don't remove WAL for temporary objects

WAL is remove by flush with GRN_WAL_ROLE_PRIMARY. We should not remove
WAL by flush. We should remove WAL by WAL recover process.

groonga/groonga,groonga/groonga,kenhys/groonga,groonga/groonga,kenhys/groonga,groonga/groonga,groonga/groonga,kenhys/groonga,kenhys/groonga,groonga/groonga,kenhys/groonga,kenhys/groonga,groonga/groonga,kenhys/groonga,kenhys/groonga,groonga/groonga