Make regression tests safe for autocommit = 'off'.

src/test/regress/expected/alter_table.out

src/test/regress/expected/copy2.out

src/test/regress/expected/domain.out

src/test/regress/expected/privileges.out

src/test/regress/expected/temp.out

src/test/regress/pg_regress.sh

src/test/regress/sql/alter_table.sql

src/test/regress/sql/copy2.sql

src/test/regress/sql/domain.sql

src/test/regress/sql/privileges.sql

src/test/regress/sql/temp.sql