Trim primary connection from new parameters

Fixes:

    : invalid dsn: invalid connection option "ssl_min_protocol_version"
    : Traceback (most recent call last):
    :   File "/usr/local/src/temboard-agent/temboardagent/plugins/monitoring/probes.py", line 793, in run
    :     dsn, connection_factory=PhysicalReplicationConnection
    :   File "/usr/local/lib/python3.6/site-packages/psycopg2/__init__.py", line 129, in connect
    :     dsn = _ext.make_dsn(dsn, **kwargs)
    :   File "/usr/local/lib/python3.6/site-packages/psycopg2/extensions.py", line 155, in make_dsn
    :     parse_dsn(dsn)
    : psycopg2.ProgrammingError: invalid dsn: invalid connection option "ssl_min_protocol_version"

temboardagent/plugins/monitoring/probes.py

@@ -114,6 +114,19 @@ def parse_primary_conninfo(pci):
     c = m.group(1).replace("''", "'")
     c = c.replace("\\'", "'")
 
+    # Keep only compat parameters because we may be bound to an old libpq.
+    well_known_params = [
+        p for p in c.split() if (
+            p.startswith('user') or
+            p.startswith('password') or
+            p.startswith('host') or
+            p.startswith('port') or
+            p.startswith('sslmode')
+        )
+    ]
+
+    c = ' '.join(well_known_params)
+
     return c