pgsql: Revert "Add GUC backtrace_on_internal_error"

Revert "Add GUC backtrace_on_internal_error"

This reverts commit a740b213d4b4d3360ad0cac696e47e5ec0eb8864.

Subsequent discussion showed that there was interest in a more general
facility to configure when server log events would produce backtraces,
and this existing limited way couldn't be extended in a compatible
way.  So the consensus was to revert this for PostgreSQL 17 and
reconsider this topic for PostgreSQL 18.

Discussion:
https://www.postgresql.org/message-id/flat/CAGECzQTChkvn5Xj772LB3%3Dxo2x_LcaO5O0HQvXqobm1xVp6%2B4w%40mail.gmail.com#764bcdbb73e162787e1ad984935e51e3

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/592a2283721f7143999364ef487f2b4993f5161d

Modified Files
--------------
doc/src/sgml/config.sgml            | 27 ---------------------------
src/backend/utils/error/elog.c      |  8 +++-----
src/backend/utils/misc/guc_tables.c | 11 -----------
src/include/utils/guc.h             |  1 -
4 files changed, 3 insertions(+), 44 deletions(-)