pgsql: Fix certificate paths to use perl2host

Fix certificate paths to use perl2host

Commit c113d8ad50 moved the copying of certificates into a temporary path
for the duration of the tests, instead of using the source tree. This broke
the tests on msys as the absolute path wasn't adapted for the msys platform.
Ensure to convert the path with perl2host before copying and passing in the
connection string.

While there also make certificate copying error handling uniform across all
the test suites.

Discussion: https://postgr.es/m/YacT3tm97xziSUFw@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/c3b34a0ff4a00d00d6ea364c85201e155ca7ef6b

Modified Files
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src/test/ssl/t/001_ssltests.pl | 21 ++++++++++++---------
src/test/ssl/t/002_scram.pl | 10 +++++++---
src/test/ssl/t/003_sslinfo.pl | 12 +++++++-----
3 files changed, 26 insertions(+), 17 deletions(-)