Handle machine deletion when NLB/LB has been deleted

[shyamradhakrishnan]

What this PR does / why we need it:
Handle machine deletion when NLB/LB has been deleted

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #347

[shyamradhakrishnan]

[SynchronizedAfterSuite] PASSED [0.000 seconds]
[SynchronizedAfterSuite]
/home/ubuntu/go/src/github.com/oracle/cluster-api-provider-oci/test/e2e/e2e_suite_test.go:261
------------------------------
[SynchronizedAfterSuite] PASSED [686.429 seconds]
[SynchronizedAfterSuite]
/home/ubuntu/go/src/github.com/oracle/cluster-api-provider-oci/test/e2e/e2e_suite_test.go:261

  Timeline >>
  STEP: Tearing down the management cluster @ 02/27/24 06:41:11.521
  << Timeline
------------------------------

Ran 7 of 28 Specs in 3274.494 seconds
SUCCESS! -- 7 Passed | 0 Failed | 0 Pending | 21 Skipped

[shyamradhakrishnan]

unit test

$ make test
GOBIN=/home/ubuntu/go/src/github.com/oracle/cluster-api-provider-oci/hack/tools/bin ./scripts/go_install.sh sigs.k8s.io/controller-runtime/tools/setup-envtest setup-envtest v0.0.0-20230131074648-f5014c077fc3
kube-builder assets: /home/ubuntu/.local/share/kubebuilder-envtest/k8s/1.24.2-linux-amd64
KUBEBUILDER_ASSETS="/home/ubuntu/.local/share/kubebuilder-envtest/k8s/1.24.2-linux-amd64" go test -coverprofile=coverage.out ./...
?   	github.com/oracle/cluster-api-provider-oci	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/config	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/metrics	[no test files]
ok  	github.com/oracle/cluster-api-provider-oci/api/v1beta1	53.928s	coverage: 23.7% of statements
ok  	github.com/oracle/cluster-api-provider-oci/api/v1beta2	0.046s	coverage: 15.6% of statements
ok  	github.com/oracle/cluster-api-provider-oci/cloud/ociutil	0.013s	coverage: 19.6% of statements
?   	github.com/oracle/cluster-api-provider-oci/cloud/scope/mocks	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/base	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/base/mock_base	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/compute	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/compute/mock_compute	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/computemanagement	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/computemanagement/mock_computemanagement	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/containerengine	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/containerengine/mock_containerengine	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/identity	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/identity/mock_identity	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/loadbalancer	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/loadbalancer/mock_lb	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/networkloadbalancer	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/networkloadbalancer/mock_nlb	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/vcn	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/cloud/services/vcn/mock_vcn	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/feature	[no test files]
?   	github.com/oracle/cluster-api-provider-oci/version	[no test files]
ok  	github.com/oracle/cluster-api-provider-oci/cloud/scope	232.072s	coverage: 75.1% of statements
ok  	github.com/oracle/cluster-api-provider-oci/cloud/util	0.084s	coverage: 61.1% of statements
ok  	github.com/oracle/cluster-api-provider-oci/controllers	26.858s	coverage: 58.7% of statements
ok  	github.com/oracle/cluster-api-provider-oci/exp/api/v1beta1	13.308s	coverage: 15.3% of statements
ok  	github.com/oracle/cluster-api-provider-oci/exp/api/v1beta2	0.016s	coverage: 4.8% of statements
ok  	github.com/oracle/cluster-api-provider-oci/exp/controllers	0.387s	coverage: 56.3% of statements
go tool cover -func=coverage.out -o coverage.txt
go tool cover -html=coverage.out -o coverage.html