[MASSMAIL]pgsql: Move libpq encryption negotiation tests

Move libpq encryption negotiation tests

The test targets libpq's options, so 'src/test/interfaces/libpq/t' is
a more natural place for it.

While doing this, I noticed that I had missed adding the
libpq_encryption subdir to the Makefile. That's why this commit only
needs to remove it from the meson.build file.

Per Peter Eisentraut's suggestion.

Discussion: https://www.postgresql.org/message-id/09d4bf5d-d0fa-4c66-a1d7-5ec757609646@eisentraut.org

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/65dfe9d167e925cd8892dedb51dde29f69b7388d

Modified Files
--------------
src/interfaces/libpq/Makefile                      |  2 +-
src/interfaces/libpq/meson.build                   |  7 ++++-
.../libpq/t/005_negotiate_encryption.pl}           |  2 +-
src/test/libpq_encryption/Makefile                 | 25 -----------------
src/test/libpq_encryption/README                   | 31 ----------------------
src/test/libpq_encryption/meson.build              | 18 -------------
src/test/meson.build                               |  1 -
7 files changed, 8 insertions(+), 78 deletions(-)