Reduce messages about implicit indexes and sequences to DEBUG1.

contrib/btree_gist/expected/not_equal.out

contrib/citext/expected/citext.out

contrib/citext/expected/citext_1.out

contrib/dblink/expected/dblink.out

contrib/pgstattuple/expected/pgstattuple.out

contrib/sepgsql/expected/ddl.out

contrib/sepgsql/expected/dml.out

contrib/tablefunc/expected/tablefunc.out

doc/src/sgml/tcn.sgml

src/backend/commands/indexcmds.c

src/backend/parser/parse_utilcmd.c

src/pl/plpython/expected/plpython_error.out

src/pl/plpython/expected/plpython_error_0.out

src/pl/plpython/expected/plpython_schema.out

src/pl/plpython/expected/plpython_subtransaction.out

src/pl/plpython/expected/plpython_subtransaction_0.out

src/pl/plpython/expected/plpython_subtransaction_5.out

src/test/regress/expected/alter_table.out

src/test/regress/expected/arrays.out

src/test/regress/expected/cluster.out