[processor/tailsampling] Add metric for sampled/not sampled spans #26910

Job	Run time
docker-build	6m 52s
collector-build	6m 31s
supervisor-test	47s
kubernetes-test-matrix (v1.26.0, receiver/k8sclusterreceiver)	4m 35s
kubernetes-test-matrix (v1.26.0, processor/k8sattributesprocessor)	3m 30s
kubernetes-test-matrix (v1.26.0, receiver/kubeletstatsreceiver)	4m 4s
kubernetes-test-matrix (v1.26.0, receiver/k8sobjectsreceiver)	3m 8s
kubernetes-test-matrix (v1.25.3, receiver/k8sclusterreceiver)	4m 37s
kubernetes-test-matrix (v1.25.3, processor/k8sattributesprocessor)	3m 25s
kubernetes-test-matrix (v1.25.3, receiver/kubeletstatsreceiver)	4m 10s
kubernetes-test-matrix (v1.25.3, receiver/k8sobjectsreceiver)	3m 23s
kubernetes-test-matrix (v1.24.7, receiver/k8sclusterreceiver)	4m 46s
kubernetes-test-matrix (v1.24.7, processor/k8sattributesprocessor)	3m 38s
kubernetes-test-matrix (v1.24.7, receiver/kubeletstatsreceiver)	4m 13s
kubernetes-test-matrix (v1.24.7, receiver/k8sobjectsreceiver)	3m 9s
kubernetes-test-matrix (v1.23.13, receiver/k8sclusterreceiver)	5m 8s
kubernetes-test-matrix (v1.23.13, processor/k8sattributesprocessor)	3m 41s
kubernetes-test-matrix (v1.23.13, receiver/kubeletstatsreceiver)	4m 26s
kubernetes-test-matrix (v1.23.13, receiver/k8sobjectsreceiver)	3m 11s
kubernetes-test	1s
	1h 17m 15s

Provide feedback