Change Dockerfile HEALTHCHECK intervals (#14317)

We should not use such a long `HEALTHCHECK` `--interval` as first task check if happening after given time, and before healthcheck returns `0` – **task won't be available** to the Docker networks – meaning that Mattermost won't work until then even if it deployed correctly!

And in Docker envs it happens often – that DB is available all the time, and just MM app is being updated. In this case even if we are healthy since 1s – we need to wait 5min until it goes online.

build/Dockerfile

@@ -31,7 +31,7 @@ RUN mkdir -p /mattermost/data /mattermost/plugins /mattermost/client/plugins \
 USER mattermost
 
 #Healthcheck to make sure container is ready
-HEALTHCHECK --interval=5m --timeout=3s \
+HEALTHCHECK --interval=30s --timeout=10s \
   CMD curl -f http://localhost:8065/api/v4/system/ping || exit 1