pgsql: Split contrib/cube platform-depended checks into separate test

Split contrib/cube platform-depended checks into separate test

We're currently maintaining two outputs for cube regression test. But that
appears to be unsuitable, because these outputs are different in out few checks
involving scientific notation. So, split checks involving scientific notation
into separate test, making contrib/cube easier to maintain. Backpatch to all
supported versions in order to make further backpatching easier.

Discussion: https://postgr.es/m/CAPpHfdvJgWjxHsJTtT%2Bo1tz3OR8EFHcLQjhp-d3%2BUcmJLh-fQA%40mail.gmail.com
Author: Alexander Korotkov
Backpatch-through: 9.3

Branch
------
REL9_4_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/41180978b4039aee5128f0e339d1a139ad2eb68e

Modified Files
--------------
contrib/cube/Makefile | 2 +-
contrib/cube/expected/cube.out | 102 ---
contrib/cube/expected/cube_1.out | 1409 ----------------------------------
contrib/cube/expected/cube_2.out | 1409 ----------------------------------
contrib/cube/expected/cube_3.out | 1409 ----------------------------------
contrib/cube/expected/cube_sci.out | 106 +++
contrib/cube/expected/cube_sci_1.out | 106 +++
contrib/cube/expected/cube_sci_2.out | 106 +++
contrib/cube/expected/cube_sci_3.out | 106 +++
contrib/cube/sql/cube.sql | 17 -
contrib/cube/sql/cube_sci.sql | 22 +
11 files changed, 447 insertions(+), 4347 deletions(-)