Make PG resource usage nicer for dev (#1615)

This overrides settings specifically in CI scenarios to the current
values but reduces the resource requirements for local dev work.

testing/dbtest/docker/postgresql.conf

@@ -1,9 +1,10 @@
 listen_addresses           = '*'      # listen on all addresses so other containers can connect if need be.
-max_connections            = 200000   # set max connections to the limit to ensure tests can always get a connection.
-                                      # Note that this may need to be decreased if <4G are available for the container.
-shared_buffers             = 256MB    # A more reasonable default compared to the 32MB default config.
+max_connections            = 1000     # set max connections a higher limit than default; this will be set to the max limit for CI runs
+                                      # the limit to ensure tests can always get a connection.
+shared_buffers             = 64MB     # A more reasonable default compared to the 32MB default config.
                                       # This gives postgres more memory for storing results. But given that short lived nature of the
                                       # test databases and the relatively small data sets, there should not be a need to increase it much more then this.
+                                      # For CI runs this is increased to 256MB.
 dynamic_shared_memory_type = posix    # Use POSIX shared memory allocated using shm_open
 fsync                      = off      # Do not flush, can cause data corruption, but since it is for tests and the data is dropped anyway...
 synchronous_commit         = off      # Do not wait for WAL records to be written to disk before reporting success