No-op old search indexing migrations which no longer run and have been obsoleted by upgrade "activities"

Summary:
See T13253. After D20200 (which changed the task schema) these migrations no longer run, since the PHP code will expect a column to exist that won't exist until a 20190220. migration runs.

We don't need these migrations, since anyone upgrading through September 2017 gets a "rebuild search indexes" activity anyway (see T11932). Just no-op them.

Test Plan: Grepped for queueDocumentForIndexing() in autopatches/, removed all of it.

Reviewers: amckinley

Reviewed By: amckinley

Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam

Differential Revision: https://secure.phabricator.com/D20243