Bump Cassandra default connect and query timeouts (grafana#2076)

See the conversation that led to this: https://cloud-native.slack.com/archives/CCYDASBLP/p1580342552117900

I personally think that 600ms is quite short, and bumping it shouldn't
have a bad effect.

Signed-off-by: Goutham Veeramachaneni <gouthamve@gmail.com>

cassandra/storage_client.go

@@ -49,8 +49,8 @@ func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
 	f.BoolVar(&cfg.Auth, "cassandra.auth", false, "Enable password authentication when connecting to cassandra.")
 	f.StringVar(&cfg.Username, "cassandra.username", "", "Username to use when connecting to cassandra.")
 	f.StringVar(&cfg.Password, "cassandra.password", "", "Password to use when connecting to cassandra.")
-	f.DurationVar(&cfg.Timeout, "cassandra.timeout", 600*time.Millisecond, "Timeout when connecting to cassandra.")
-	f.DurationVar(&cfg.ConnectTimeout, "cassandra.connect-timeout", 600*time.Millisecond, "Initial connection timeout, used during initial dial to server.")
+	f.DurationVar(&cfg.Timeout, "cassandra.timeout", 2*time.Second, "Timeout when connecting to cassandra.")
+	f.DurationVar(&cfg.ConnectTimeout, "cassandra.connect-timeout", 5*time.Second, "Initial connection timeout, used during initial dial to server.")
 	f.IntVar(&cfg.Retries, "cassandra.max-retries", 0, "Number of retries to perform on a request. (Default is 0: no retries)")
 	f.DurationVar(&cfg.MinBackoff, "cassandra.retry-min-backoff", 100*time.Millisecond, "Minimum time to wait before retrying a failed request. (Default = 100ms)")
 	f.DurationVar(&cfg.MaxBackoff, "cassandra.retry-max-backoff", 10*time.Second, "Maximum time to wait before retrying a failed request. (Default = 10s)")