pgsql: Switch EXPLAIN to unaligned output for json/xml/yaml

Switch EXPLAIN to unaligned output for json/xml/yaml

Use unaligned output for multiple EXPLAIN queries using non-text format
in regression tests. With aligned output adding/removing explain fields
can be very disruptive, as it often modifies the whole block because of
padding. Unaligned output does not have this issue.

Author: Tomas Vondra <tomas(at)vondra(dot)me>
Reviewed-by: Melanie Plageman <melanieplageman(at)gmail(dot)com>
Reviewed-by: Lukas Fittl <lukas(at)fittl(dot)com>
Reviewed-by: Andres Freund <andres(at)anarazel(dot)de>
Discussion: https://postgr.es/m/flat/a177a6dd-240b-455a-8f25-aca0b1c08c6e%40vondra.me

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/10d5a12a93150deb15f600492bbd4e46a2212b3b

Modified Files
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src/test/regress/expected/explain.out | 296 +++++++++++++++++-----------------
src/test/regress/sql/explain.sql | 5 +-
2 files changed, 150 insertions(+), 151 deletions(-)