[v0.9][SURE-7311] GitRepo fails with error "namespace not found" when using namespaceLabels: in existing namespaces about fleet

[mmartin24]

Checked in 2.8.3-rc3 as follows:

System Information
For fresh installation

• Rancher version: 2.8.3-rc3
• Fleet Version: 0.9.1-rc.6
• Kubernetes version: v1.28.7+k3s1

For upgrade installation

• Rancher version: 2.7.9
• Fleet Version: 0.8.0
• Kubernetes version: v1.26.10+k3s2
• Later upgrade to Rancher 2.8.3-rc3

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Installation and Testing

Scenario 1 - Test gitrepo succeeds when using namespaceLabels in existing namespace on fresh Rancher installation

• Fresh installation of Rancher 2.8.3-rc3
• Deployed local GitRepo using `defaultNamespace: nginx'.
• Observed no error appeared due to namespace not found and cluster is ready.

Scenario 2 - Test failed gitrepo with error "namespace not found" when using namespaceLabels: in existing namespaces is fixed after Rancher upgrade to 2.8.3-rc3

• Deploy local GitRepo using defaultNamespace: nginx on Rancher 2.7.9 (example here)
• Observe error 'Namespace "nginx" not found' appears and cluster is not ready
• Upgrade to Rancher 2.8.3-rc3
• Observe no error appeared due to namespace not found and cluster is ready.

Scenario 3 - Test failed gitrepo with error "namespace not found" when using namespaceLabels: in existing namespaces on downstream cluster is fixed after Rancher upgrade to 2.8.3-rc3 *

• Deploy Rancher 2.7.9
• Deploy downtream cluster
• Create namespace nginx in it.
• Deploy GitRepo using `defaultNamespace: nginx'
• Observe error 'Namespace "nginx" not found' appears and cluster is not ready
• Upgrade to Rancher 2.8.3-rc3
• Observe no error appeared due to namespace not found and cluster is ready.

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Screenshots
Broken vs Fixed

Broken version fixed after upgrade