[Platform] K8s universe names need to be sanitized for auto-generated K8s namespaces

[jvigil-yugabyte]

When the K8s provider configuration does not specify the namespace name to use, the paltform attempts to automatically create a namespace for each Universe and gives it a name based on the deployment type, region/zone, and Universe name. By default, Kubernetes restricts the allowed namespace names following this regex pattern: [a-z0-9]([-a-z0-9]*[a-z0-9])?. So, it is possible for the user to specify input that would cause an invalid namespace name to be used, which causes the universe creation to fail. There are a couple different ways to handle this. 1) Restrict the allowed region/zone/universe names 2) Automatically sanitize the input.

Example error encountered when attempting to create a Universe name "ShashankTest":

Caused by: java.lang.RuntimeException: The Namespace "yb-dev-ShashankTest-us-west1-a" is invalid: metadata.name: Invalid value: "yb-dev-ShashankTest-us-west1-a": a DNS-1123 label must consist of lower case alphanumeric characters or '-', and must start and end with an alphanumeric character (e.g. 'my-name',  or '123-abc', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?')
	at com.yugabyte.yw.commissioner.AbstractTaskBase.processShellResponse(AbstractTaskBase.java:113)
	at com.yugabyte.yw.commissioner.tasks.subtasks.KubernetesCommandExecutor.run(KubernetesCommandExecutor.java:222)
	... 5 common frames omitted

[jvigil-yugabyte]

CC: @iSignal

[iSignal]

Good catch! We don't have to name the namespaces after the name of the cluster really, so something like sanitize(clustername)+random_hash(10 chars) might work.

Alternately, when we move to the "new naming convention" we can stop creating a separate namespace per AZ (the current method actually prevents us from generating a single LB for multi-AZ scenarios).