In relevant log messages, indicate whether vacuums are aggressive.
In relevant log messages, indicate whether vacuums are aggressive.

Kyotaro Horiguchi, reviewed Masahiko Sawada, David G. Johnston, Álvaro
Herrera, and me.  Grammar correction to the final posted patch by me.

Discussion: bfdb2235468b0d414994e3d4d97552b54d870ebb@lab.ntt.co.jp

50wu/gpdb,adam8157/gpdb,lisakowen/gpdb,xinzweb/gpdb,greenplum-db/gpdb,50wu/gpdb,50wu/gpdb,lisakowen/gpdb,xinzweb/gpdb,xinzweb/gpdb,50wu/gpdb,lisakowen/gpdb,lisakowen/gpdb,lisakowen/gpdb,50wu/gpdb,lisakowen/gpdb,adam8157/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,adam8157/gpdb,adam8157/gpdb,50wu/gpdb,xinzweb/gpdb,xinzweb/gpdb,adam8157/gpdb,xinzweb/gpdb,adam8157/gpdb,xinzweb/gpdb,adam8157/gpdb,lisakowen/gpdb,lisakowen/gpdb,xinzweb/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,50wu/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,adam8157/gpdb,greenplum-db/gpdb,50wu/gpdb