Run test utility containers with tini (#633)

This should help speed up test teardown, since they handle SIGTERM
instead of having to wait for the container shutdown to timeout.

Author: nightkr

tests/templates/kuttl/logging/06-install-hdfs-test-runner.yaml

@@ -15,8 +15,10 @@ spec:
       labels:
         app: hdfs-test-runner
     spec:
+      shareProcessNamespace: true
       containers:
         - name: hdfs-test-runner
           image: docker.stackable.tech/stackable/testing-tools:0.2.0-stackable0.0.0-dev
+          args: [sleep, infinity]
           stdin: true
           tty: true

tests/templates/kuttl/smoke/40-webhdfs.yaml

@@ -15,9 +15,11 @@ spec:
       labels:
         app: webhdfs
     spec:
+      shareProcessNamespace: true
       containers:
         - name: webhdfs
           image: docker.stackable.tech/stackable/testing-tools:0.2.0-stackable0.0.0-dev
+          args: [sleep, infinity]
           stdin: true
           tty: true
           resources: