postgres_fdw: Remove unstable regression test.

Robert Haas <rhaas@postgresql.org>

Commit: bb4df42e6a394ce77801b6952b6dc8b43d91fea7
Author: Robert Haas <rhaas@postgresql.org>
Date: 2016-02-09T20:42:20Z
Releases: 9.6.0
postgres_fdw: Remove unstable regression test.

Per Tom Lane and the buildfarm.

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