fix(matrix): Increase memory requests and limits for database

This patch increases the memory requests and limits for the matrix
postgres database in order to ensure good performance and the expected
availability. The current database uses almost 2 GiB of RAM. However,
it's mostly filesystem caching. This patch should help to utilise the
RAM better than leaving it just idle.

apps/base/matrix/database.yaml

@@ -24,7 +24,7 @@ spec:
   resources:
     requests:
       cpu: 200m
-      memory: 512Mi
+      memory: 2048Mi
     limits:
       cpu: "1"
-      memory: 2048Mi
+      memory: 3072Mi