change cassandra db plugin timeout to 5s as in docs (#12443)

* fix cassandra db plugin timeout to 5s as in docs

Documentation says timeout is 5s, but code uses 0s, which is too short any any real world usage, causing issues.
https://www.vaultproject.io/api/secret/databases/cassandra#connect_timeout
issues: https://github.com/hashicorp/vault/issues/8527 https://github.com/hashicorp/vault/issues/9400

* Create 12443.txt

changelog entry

changelog/12443.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+secrets/database/cassandra: change connect_timeout to 5s as documentation says
+```

plugins/database/cassandra/connection_producer.go

@@ -60,7 +60,7 @@ func (c *cassandraConnectionProducer) Initialize(ctx context.Context, req dbplug
 	}
 
 	if c.ConnectTimeoutRaw == nil {
-		c.ConnectTimeoutRaw = "0s"
+		c.ConnectTimeoutRaw = "5s"
 	}
 	c.connectTimeout, err = parseutil.ParseDurationSecond(c.ConnectTimeoutRaw)
 	if err != nil {