Backport of added check if anonymous token policy exists into release/1.2.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #2790 to be assessed for backporting due to the inclusion of the label backport/1.2.x.

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The person who merged in the original PR is:
@aahel
This person should manually cherry-pick the original PR into a new backport PR,
and close this one when the manual backport PR is merged in.

merge conflict error: POST https://api.github.com/repos/hashicorp/consul-k8s/merges: 409 Merge conflict []

The below text is copied from the body of the original PR.

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Changes proposed in this PR:

Prevent updating anonymous token if it already exists and is attached to the anonymous token policy

How I've tested this PR:

• setup the deafault partiton and create a non-default partition called my-partition.
• modified the anonymous token policy rule.
• created helm deployment in my-partiton using acl bootstrap token with following policies.

acl = "read"
operator = "read"
agent_prefix "" {
  policy = "read"
}

partition "my-partition" {
  acl = "write"
  mesh = "write"
  peering = "write"
  namespace_prefix "" {
    policy = "write"
  }
  service_prefix "" {
    policy = "write"
  }
}

• server-acl-acl init was successfull and anonymous token policy rule didn't get updated

How I expect reviewers to test this PR:

Checklist:

• Tests added
• CHANGELOG entry added

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Overview of commits

• deecdb9 - 8d89601 - 10946ed - 18c2824 - 78d17e7 - 525e56b - 977050c - 0d4e107 - 905e681