pgsql: pg_upgrade: Don't use separate installation for test.

pg_upgrade: Don't use separate installation for test.

For pg_upgrade's test we (unless prevented by the caller via via
NO_TEMP_INSTALL) built a separate installation. That causes an
unnecessary slowdown after the infrastructure introduced by
dcae5faccab (and unnecessarily duplicates code).

Author: Andres Freund
Reviewed-By: Tom Lane
Discussion:
    https://postgr.es/m/20190521191918.z7kwnrlj45mk2k67@alap3.anarazel.de
    https://postgr.es/m/20190521195209.qfzwfxvymguuwlu5@alap3.anarazel.de

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/7005389b2ad17258bc3aa0a2427c4eb77fed1d09

Modified Files
--------------
src/bin/pg_upgrade/Makefile | 14 ++------------
src/bin/pg_upgrade/test.sh  | 30 +++---------------------------
2 files changed, 5 insertions(+), 39 deletions(-)