pgsql: Revert "Add GUC checks for ssl_min_protocol_version and ssl_max_

Revert "Add GUC checks for ssl_min_protocol_version and ssl_max_protocol_version"

This reverts commit 41aadee, as the GUC checks could run on older values
with the new values used, and result in incorrect errors if both
parameters are changed at the same time.

Per complaint from Tom Lane.

Discussion: https://postgr.es/m/27574.1581015893@sss.pgh.pa.us
Backpatch-through: 12

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/414c2fd1e1c0ccd1af1cad046bef1264e3f4347f

Modified Files
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src/backend/utils/misc/guc.c   | 51 ++----------------------------------------
src/test/ssl/t/001_ssltests.pl | 20 +----------------
2 files changed, 3 insertions(+), 68 deletions(-)