[googlecloudspannerreceiver] Mark the component as unmaintained #34549

Job	Run time
docker-build	7m 30s
collector-build	7m 23s
supervisor-test	48s
kubernetes-test-matrix (v1.26.0, receiver/k8sclusterreceiver)	4m 56s
kubernetes-test-matrix (v1.26.0, processor/k8sattributesprocessor)	4m 20s
kubernetes-test-matrix (v1.26.0, receiver/kubeletstatsreceiver)	4m 24s
kubernetes-test-matrix (v1.26.0, receiver/k8sobjectsreceiver)	3m 21s
kubernetes-test-matrix (v1.25.3, receiver/k8sclusterreceiver)	5m 0s
kubernetes-test-matrix (v1.25.3, processor/k8sattributesprocessor)	4m 27s
kubernetes-test-matrix (v1.25.3, receiver/kubeletstatsreceiver)	4m 12s
kubernetes-test-matrix (v1.25.3, receiver/k8sobjectsreceiver)	3m 48s
kubernetes-test-matrix (v1.24.7, receiver/k8sclusterreceiver)	5m 14s
kubernetes-test-matrix (v1.24.7, processor/k8sattributesprocessor)	4m 40s
kubernetes-test-matrix (v1.24.7, receiver/kubeletstatsreceiver)	4m 20s
kubernetes-test-matrix (v1.24.7, receiver/k8sobjectsreceiver)	3m 35s
kubernetes-test-matrix (v1.23.13, receiver/k8sclusterreceiver)	4m 58s
kubernetes-test-matrix (v1.23.13, processor/k8sattributesprocessor)	4m 41s
kubernetes-test-matrix (v1.23.13, receiver/kubeletstatsreceiver)	4m 27s
kubernetes-test-matrix (v1.23.13, receiver/k8sobjectsreceiver)	3m 24s
kubernetes-test	1s
	1h 25m 29s

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