pgsql: Revert "docs: change "default role" wording to "predefined role"

Revert "docs: change "default role" wording to "predefined role""

This reverts commit 0e936a2148472e6c364aee8c3e298dc16dc4240a.

Per discussion, we can't change the section title without some
web-site work, so revert this change temporarily.

Discussion: https://postgr.es/m/157742545062.1149.11052653770497832538@wrigleys.postgresql.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c185a57753e64fe3ffc996ea18da8672b302a5a4

Modified Files
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doc/src/sgml/monitoring.sgml |  2 +-
doc/src/sgml/user-manag.sgml | 28 ++++++++++++++--------------
2 files changed, 15 insertions(+), 15 deletions(-)