pgsql: EUC_CN, EUC_JP, EUC_KR, EUC_TW: Skip U+00A0 tests instead of fai

EUC_CN, EUC_JP, EUC_KR, EUC_TW: Skip U+00A0 tests instead of failing.

Settings that ran the new test euc_kr.sql to completion would fail these
older src/pl tests. Use alternative expected outputs, for which psql
\gset and \if have reduced the maintenance burden. This fixes
"LANG=ko_KR.euckr LC_MESSAGES=C make check-world". (LC_MESSAGES=C fixes
IO::Pty usage in tests 010_tab_completion and 001_password.) That file
is new in commit c67bef3f3252a3a38bf347f9f119944176a796ce. Back-patch
to v14, like that commit.

Discussion: https://postgr.es/m/20260217184758.da.noahmisch@microsoft.com
Backpatch-through: 14

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/0163951b785e9b839706ce8e557066ad083beef1

Modified Files
--------------
src/pl/plperl/GNUmakefile | 2 +-
src/pl/plperl/expected/plperl_elog.out | 13 -------------
src/pl/plperl/expected/plperl_elog_1.out | 13 -------------
src/pl/plperl/expected/plperl_unicode.out | 18 ++++++++++++++++++
src/pl/plperl/expected/plperl_unicode_1.out | 10 ++++++++++
src/pl/plperl/meson.build | 1 +
src/pl/plperl/sql/plperl_elog.sql | 15 ---------------
src/pl/plperl/sql/plperl_unicode.sql | 19 +++++++++++++++++++
src/pl/plpython/expected/plpython_unicode.out | 13 +++++++++----
src/pl/plpython/expected/plpython_unicode_1.out | 12 ++++++++++++
src/pl/plpython/sql/plpython_unicode.sql | 13 +++++++++----
src/pl/tcl/expected/pltcl_unicode.out | 13 +++++++++----
src/pl/tcl/expected/pltcl_unicode_1.out | 12 ++++++++++++
src/pl/tcl/sql/pltcl_unicode.sql | 13 +++++++++----
14 files changed, 109 insertions(+), 58 deletions(-)