pgsql: Fix portability issues in the new gist pageinspect test.

Fix portability issues in the new gist pageinspect test.

1. The raw bytea representation of the point-type keys used in the test
depends on endianess. Remove the raw key_data column from the test.

2. The items stored on non-leftmost gist page depends on how many items
git on the other pages. This showed up as a failure on 32-bit i386
systems. To fix, only test the gist_page_items() function on the
leftmost leaf page.

Per Andrey Borodin and the buildfarm.

Discussion: https://www.postgresql.org/message-id/9FCEC1DC-86FB-4A57-88EF-DD13663B36AF%40yandex-team.ru

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/6ecaaf810b8b9e3132f00549e630400f38a7ca37

Modified Files
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contrib/pageinspect/expected/gist.out | 52 ++++++++---------------------------
contrib/pageinspect/sql/gist.sql | 7 ++---
2 files changed, 15 insertions(+), 44 deletions(-)