Remove useless code in ExecInitModifyTable

When Who What
2018-01-17 19:44:30 Tom Lane (tgl) Closed in commitfest 2018-01 with status: Committed
2018-01-17 19:29:00 Tom Lane (tgl) Added tgl as committer
2018-01-15 02:36:29 Amit Langote (amitlan) New status: Ready for Committer
2018-01-15 02:36:24 Amit Langote (amitlan) Added amitlan as reviewer
2017-11-28 02:18:19 Michael Paquier (michael-kun) Closed in commitfest 2017-11 with status: Moved to next CF
2017-11-28 02:14:53 Michael Paquier (michael-kun) New status: Needs review
2017-09-05 03:41:50 Ryan Murphy (murftown) Posted comment with messageid <20170905034150.18925.61271.pgcf@coridan.postgresql.org>
2017-09-05 03:41:50 Ryan Murphy (murftown) New status: Waiting on Author
2017-09-04 03:44:42 Etsuro Fujita (efujita) Changed authors to Etsuro Fujita (efujita)
2017-09-04 03:44:05 Etsuro Fujita (efujita) Attached mail thread 93cf9816-2f7d-0f67-8ed2-4a4e497a6ab8@lab.ntt.co.jp
2017-09-04 03:44:05 Etsuro Fujita (efujita) Created patch record