Align federated helmreleases.helm.toolkit.fluxcd.io observedGeneration semantics with its native

[yike21]

What type of PR is this?
/kind feature

What this PR does / why we need it:

Which issue(s) this PR fixes:
Part of #4870

Special notes for your reviewer:

Does this PR introduce a user-facing change?:
NONE

`karmada-controller-manager`: Mark `.status.observedGeneration` of helmreleases.helm.toolkit.fluxcd.io with `.metadata.generation` only when all members' statuses are algined with its resource template generation.

[yike21]

Use karmadactl interpret to view test results:

## Execute the statusAggregation rule
$ karmadactl interpret -f customizations.yaml --operation aggregateStatus --desired-file testdata/observed-helmrelease.yaml  --status-file testdata/status-file.yaml 
---
# [1/1] aggregatedStatus:
apiVersion: helm.toolkit.fluxcd.io/v2beta1
kind: HelmRelease
metadata:
    annotations:
        resourcetemplate.karmada.io/generation: "1"
    generation: 1
    name: sample
    namespace: default
spec:
    chart:
        spec:
            chart: ./charts/podinfo
            interval: 1m
            sourceRef:
                kind: GitRepository
                name: podinfo
                namespace: default
            verify:
                secretRef:
                    name: fake-verify-secret
            version: '>=4.0.0 <5.0.0'
    interval: 5m
    kubeConfig:
        secretRef:
            name: fake-secret
    serviceAccountName: fake-sa
    test:
        enable: true
        ignoreFailures: true
    valuesFrom:
        - kind: ConfigMap
          name: fake-configmap
status:
    conditions:
        - lastTransitionTime: "2023-05-01T07:11:16Z"
          message: member1=Release reconciliation succeeded, member3=Release reconciliation succeeded
          reason: ReconciliationSucceeded
          status: "True"
          type: Ready
        - lastTransitionTime: "2023-05-01T07:11:16Z"
          message: member1=Helm install succeeded, member3=Helm install succeeded
          reason: InstallSucceeded
          status: "True"
          type: Released
    helmChart: test-helmrelease/test-helmrelease-sample
    lastAppliedRevision: 6.3.5
    lastAttemptedRevision: 6.3.5
    lastAttemptedValuesChecksum: da39a3ee5e6b4b0d3255bfef95601890afd80709
    lastReleaseRevision: 1
    observedGeneration: 1

## Execute the statusReflection rule
$ karmadactl interpret -f customizations.yaml --operation interpretStatus --observed-file testdata/observed-helmrelease.yaml 
---
# [1/1] status:
conditions:
    - lastTransitionTime: "2023-05-01T07:11:16Z"
      message: Release reconciliation succeeded
      reason: ReconciliationSucceeded
      status: "True"
      type: Ready
    - lastTransitionTime: "2023-05-01T07:11:16Z"
      message: Helm install succeeded
      reason: InstallSucceeded
      status: "True"
      type: Released
generation: 1
helmChart: test-helmrelease/test-helmrelease-sample
lastAppliedRevision: 6.3.5
lastAttemptedRevision: 6.3.5
lastAttemptedValuesChecksum: da39a3ee5e6b4b0d3255bfef95601890afd80709
lastReleaseRevision: 1
observedGeneration: 1
resourceTemplateGeneration: 1

There's one more task that needs to be done: writing a description of the test methodology.
I'll try to get it done this week :)

[yike21]

/cc @chaunceyjiang @XiShanYongYe-Chang Please take a look~

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All modified and coverable lines are covered by tests ✅

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@@           Coverage Diff           @@
##           master    #5311   +/-   ##
=======================================
  Coverage   28.38%   28.38%           
=======================================
  Files         632      632           
  Lines       43801    43801           
=======================================
  Hits        12432    12432           
  Misses      30464    30464           
  Partials      905      905           

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[XiShanYongYe-Chang]

Thanks a lot @yike21

[XiShanYongYe-Chang]

Thanks @yike21
/lgtm

[chaunceyjiang]

Thanks~

[karmada-bot]

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