Changing TargetNamespace Causes Rollback Failure on Update

When there is a change to the `spec.targetNamespace` is changed in the application group, the reconciler is unable to rollback the previous workflow as it can't find the previous one

```
2021-04-10T19:47:29.611Z ERROR controllers.ApplicationGroup failed to rollback failed HelmRelease instances {"appgroup": "bookinfo", "error": "release: not found", "errorVerbose": "release: not found\nhelm.sh/helm/v3/pkg/storage/driver.init\n\t/go/pkg/mod/helm.sh/helm/v3@v3.1.2/pkg/storage/driver/driver.go:27\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5228\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:190\nruntime.goexit\n\t/usr/local/go/src/runtime/asm_amd64.s:1357"}
2021-04-10T19:47:29.611Z ERROR controller-runtime.controller Reconciler error {"controller": "applicationgroup", "request": "/bookinfo", "error": "release: not found", "errorVerbose": "release: not found\nhelm.sh/helm/v3/pkg/storage/driver.init\n\t/go/pkg/mod/helm.sh/helm/v3@v3.1.2/pkg/storage/driver/driver.go:27\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5228\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:190\nruntime.goexit\n\t/usr/local/go/src/runtime/asm_amd64.s:1357"}
2021-04-10T19:47:34.733Z ERROR controllers.ApplicationGroup {"appgroup": "bookinfo", "error": "workflow in failure/error condition : helmrelease in failure status"}
2021-04-10T19:47:34.768Z INFO controllers.ApplicationGroup Remediating the applicationgroup with helmrelease failure status {"appgroup": "bookinfo"}
2021-04-10T19:47:34.768Z DEBUG controller-runtime.manager.events Warning {"object": {"kind":"ApplicationGroup","name":"bookinfo","uid":"9d8f0d37-d60a-49c3-817d-3039c545ca3b","apiVersion":"orkestra.azure.microsoft.com/v1alpha1","resourceVersion":"2260"}, "reason": "ReconcileError", "message": "Failed to reconcile ApplicationGroup bookinfo with Error : workflow in failure/error condition : helmrelease in failure status"}
2021-04-10T19:47:34.777Z ERROR controllers.ApplicationGroup failed to rollback failed HelmRelease instances {"appgroup": "bookinfo", "error": "release: not found", "errorVerbose": "release: not found\nhelm.sh/helm/v3/pkg/storage/driver.init\n\t/go/pkg/mod/helm.sh/helm/v3@v3.1.2/pkg/storage/driver/driver.go:27\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5228\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.doInit\n\t/usr/local/go/src/runtime/proc.go:5223\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:190\nruntime.goexit\n\t/usr/local/go/src/runtime/asm_amd64.s:1357"}
```