Restrict vertical tightness to parentheses in Perl code

Restrict vertical tightness to parentheses in Perl code

The vertical tightness settings collapse vertical whitespace between
opening and closing brackets (parentheses, square brakets and braces).
This can make data structures in particular harder to read, and is not
very consistent with our style in non-Perl code. This patch restricts
that setting to parentheses only, and reformats all the perl code
accordingly. Not applying this to parentheses has some unfortunate
effects, so the consensus is to keep the setting for parentheses and not
for the others.

The diff for this patch does highlight some places where structures
should have trailing commas. They can be added manually, as there is no
automatic tool to do so.

Discussion: https://postgr.es/m/a2f2b87c-56be-c070-bfc0-36288b4b41c1@2ndQuadrant.com