Remove -default-protocol and annotation support

[lkysow]

Changes proposed in this PR:

• Remove support for -default-protocol and -enable-central-config flags passed to consul-k8s inject-connect command. These flags would cause Consul to write a service-defaults config entry that would set the protocol of the service.
• Remove support for the consul.hashicorp.com/connect-service-protocol annotation. Connect pods that have this annotation will not be injected and the injector will return an error.

How I've tested this PR:

• Using ghcr.io/lkysow/consul-k8s-dev:jan11 I created a service that sets the annotation and confirmed the replicaset won't start with error:

  Error creating: admission webhook "consul-connect-injector.consul.hashicorp.com" denied the request: Error validating pod: 
  the consul.hashicorp.com/connect-service-protocol annotation is no longer supported. Instead, create a ServiceDefaults 
  resource (see www.consul.io/docs/k8s/crds/upgrade-to-crds)
  

How I expect reviewers to test this PR:

• code

Checklist:

• Tests added
• CHANGELOG entry added (HashiCorp engineers only, community PRs should not add a changelog entry)

Companion to: hashicorp/consul-helm#763

[thisisnotashwin]

Looks great!! Good work @lkysow 🦊

[ishustava]

Looks perfect! Looking at all the code removals gives you such a satisfying feeling 😃