fix: avoid creating duplicate urs for background policies

[realshuting]

Explanation

This PR fixes duplicate urs creation for the same rule. The issue happens when a background policy has generateExisting or mutateExistingOnPolicyUpdate enabled.

When such a policy is created:

• before this change:

27 updaterequests are created for 3 matching triggers, 3 rules

• after this change:

9 updaterequests are created for 3 matching triggers, 3 rules

policy:

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: zk-kafka-address
spec:
  generateExisting: true
  rules:
  - exclude:
      any:
      - resources:
          namespaces:
          - kube-system
          - default
          - kube-public
          - kyverno
          - local-path-storage
    generate:
      apiVersion: v1
      data:
        data:
          KAFKA_ADDRESS: 192.168.10.13:9092,192.168.10.14:9092,192.168.10.15:9092
          ZK_ADDRESS: 192.168.10.10:2181,192.168.10.11:2181,192.168.10.12:2181
        kind: ConfigMap
        metadata:
          labels:
            somekey: somevalue
      kind: ConfigMap
      name: zk-kafka-address
      namespace: '{{request.object.metadata.name}}'
      synchronize: true
    match:
      any:
      - resources:
          kinds:
          - Namespace
    name: k-kafka-address
  - exclude:
      any:
      - resources:
          namespaces:
          - kube-system
          - default
          - kube-public
          - kyverno
          - local-path-storage
    generate:
      apiVersion: v1
      data:
        data:
          KAFKA_ADDRESS: 192.168.10.13:9092,192.168.10.14:9092,192.168.10.15:9092
          ZK_ADDRESS: 192.168.10.10:2181,192.168.10.11:2181,192.168.10.12:2181
        kind: ConfigMap
        metadata:
          labels:
            somekey: somevalue
      kind: ConfigMap
      name: zk-kafka-address-2
      namespace: '{{request.object.metadata.name}}'
      synchronize: true
    match:
      any:
      - resources:
          kinds:
          - Namespace
    name: k-kafka-address-2
  - exclude:
      any:
      - resources:
          namespaces:
          - kube-system
          - default
          - kube-public
          - kyverno
          - local-path-storage
    generate:
      apiVersion: v1
      data:
        data:
          KAFKA_ADDRESS: 192.168.10.13:9092,192.168.10.14:9092,192.168.10.15:9092
          ZK_ADDRESS: 192.168.10.10:2181,192.168.10.11:2181,192.168.10.12:2181
        kind: ConfigMap
        metadata:
          labels:
            somekey: somevalue
      kind: ConfigMap
      name: zk-kafka-address-3
      namespace: '{{request.object.metadata.name}}'
      synchronize: true
    match:
      any:
      - resources:
          kinds:
          - Namespace
    name: k-kafka-address-3

Related issue

#9633

Milestone of this PR

Documentation (required for features)

My PR contains new or altered behavior to Kyverno.

• I have sent the draft PR to add or update the documentation and the link is:

What type of PR is this

Proposed Changes

Proof Manifests

Checklist

• I have read the contributing guidelines.
• I have read the PR documentation guide and followed the process including adding proof manifests to this PR.
• This is a bug fix and I have added unit tests that prove my fix is effective.
• This is a feature and I have added CLI tests that are applicable.
• My PR needs to be cherry picked to a specific release branch which is .
• My PR contains new or altered behavior to Kyverno and
  • CLI support should be added and my PR doesn't contain that functionality.

Further Comments

[realshuting]

/cherry-pick release-1.12

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 38 lines in your changes missing coverage. Please review.

Project coverage is 10.02%. Comparing base (6813fc0) to head (41ffc3f).
Report is 1 commits behind head on main.

❗ Current head 41ffc3f differs from pull request most recent head f0800af

Please upload reports for the commit f0800af to get more accurate results.

Files	Patch %	Lines
pkg/policy/mutate.go	0.00%	22 Missing ⚠️
pkg/policy/generate.go	0.00%	11 Missing ⚠️
pkg/policy/policy_controller.go	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10431      +/-   ##
==========================================
- Coverage   10.03%   10.02%   -0.01%     
==========================================
  Files        1041     1041              
  Lines       93857    93864       +7     
==========================================
  Hits         9414     9414              
- Misses      83407    83414       +7     
  Partials     1036     1036              

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