pgsql: Fix various infelicities that have snuck into usage of

Log Message:
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Fix various infelicities that have snuck into usage of errdetail() and
friends. Avoid double translation of some messages, ensure other messages
are exposed for translation (and make them follow the style guidelines),
avoid unsafe passing of an unpredictable message text as a format string.

Modified Files:
--------------
pgsql/src/backend/catalog:
aclchk.c (r1.143 -> r1.144)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/aclchk.c?r1=1.143&r2=1.144)
pg_shdepend.c (r1.23 -> r1.24)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/pg_shdepend.c?r1=1.23&r2=1.24)
pgsql/src/backend/commands:
vacuumlazy.c (r1.104 -> r1.105)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/vacuumlazy.c?r1=1.104&r2=1.105)
pgsql/src/backend/utils/adt:
xml.c (r1.69 -> r1.70)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/xml.c?r1=1.69&r2=1.70)