Bump up signaltometrics connector to alpha stability #50568

Job	Run time
collector-build	6m 48s
docker-build	7m 15s
supervisor-test	55s
kubernetes-test-matrix (v1.30.0, receiver/k8sclusterreceiver)	6m 23s
kubernetes-test-matrix (v1.30.0, processor/k8sattributesprocessor)	8m 9s
kubernetes-test-matrix (v1.30.0, receiver/kubeletstatsreceiver)	4m 1s
kubernetes-test-matrix (v1.30.0, receiver/k8sobjectsreceiver)	2m 58s
kubernetes-test-matrix (v1.23.17, receiver/k8sclusterreceiver)	6m 30s
kubernetes-test-matrix (v1.23.17, processor/k8sattributesprocessor)	8m 8s
kubernetes-test-matrix (v1.23.17, receiver/kubeletstatsreceiver)	4m 1s
kubernetes-test-matrix (v1.23.17, receiver/k8sobjectsreceiver)	3m 15s
kubernetes-test	1s
	58m 24s

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