Wait for Mimir to be installed in k8s integration test (#5064)

Author: ptodev

internal/cmd/integration-tests-k8s/tests/mimir-alerts-kubernetes/testdata/setup.sh

@@ -10,4 +10,4 @@ kubectl create namespace mimir-test
 helm repo add grafana https://grafana.github.io/helm-charts
 helm repo update
 # TODO: Upgrade to version 6 of Mimir's Helm chart.
-helm -n mimir-test install mimir grafana/mimir-distributed --version 5.8.0
+helm -n mimir-test install mimir grafana/mimir-distributed --version 5.8.0 --wait