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_3_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/5d6a1ee9a50f60324aa177fc0f64b7e66e479fb4

Modified Files
--------------
contrib/cube/Makefile | 2 +-
contrib/cube/expected/cube.out | 102 ---
contrib/cube/expected/cube_1.out | 1128 ----------------------------------
contrib/cube/expected/cube_2.out | 1128 ----------------------------------
contrib/cube/expected/cube_3.out | 1128 ----------------------------------
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(+), 3504 deletions(-)