[server] Reduce DB healthcheck interval in starter Docker compose template (#2263)

The museum container depends on the postgres container being up and the
DB being ready to accept connections. To enforce this dependency, we use
the healthcheck attribute.

See: https://docs.docker.com/compose/startup-order/

The value of the healthcheck interval was set to 1s since the default
(30s) caused each `docker compose up` to require at least 30 seconds on
each startup, which was prohibitive. The downside is that the
healthchecks continue to run beyond the startup phase too, and for small
VMs, this caused a lot of unnecessary CPU usage.

Thankfully, now Docker has a new option for a different healthcheck
during the start phase:

> start interval is the time between health checks during the start
period. This
  option requires Docker Engine version 25.0 or later.

They were added in Docker compose 2.20.2, released an year ago
(2023-07-19).

https://docs.docker.com/compose/release-notes/#2202

server/compose.yaml

@@ -49,9 +49,8 @@ services:
           "-U",
           "pguser"
         ]
-      interval: 1s
-      timeout: 5s
-      retries: 20
+      start_period: 40s
+      start_interval: 1s
     volumes:
       - postgres-data:/var/lib/postgresql/data
     networks: