pgsql: Doc: fix up PDF build warnings from over-width table columns.

Doc: fix up PDF build warnings from over-width table columns.

Addition of multirange info to tables 8.27 and 65.1 made them start
throwing "exceed the available area" warnings in PDF docs builds.

For 8.27, twiddling the existing column width hints was enough to
fix this.  For 65.1, I twiddled the widths a little, but to really
fix it I had to insert a space after each comma in the table, to
allow a line break to occur there.  (This seemed easier to read
and maintain than the alternative of inserting &zwsp; entities.)

Per buildfarm.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/f20dc2c8dd50a5c738d535205d5d44bff82d3f75

Modified Files
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doc/src/sgml/datatype.sgml |   4 +-
doc/src/sgml/gist.sgml     | 211 +++++++++++++++++++++++----------------------
2 files changed, 109 insertions(+), 106 deletions(-)