[exporter/loadbalancing] Fix memory leaks #28206

Job	Run time
collector-build	5m 10s
docker-build	5m 33s
supervisor-test	57s
kubernetes-test-matrix (v1.26.0, receiver/k8sclusterreceiver)	4m 56s
kubernetes-test-matrix (v1.26.0, processor/k8sattributesprocessor)	3m 18s
kubernetes-test-matrix (v1.26.0, receiver/kubeletstatsreceiver)	4m 20s
kubernetes-test-matrix (v1.26.0, receiver/k8sobjectsreceiver)	3m 18s
kubernetes-test-matrix (v1.25.3, receiver/k8sclusterreceiver)	5m 5s
kubernetes-test-matrix (v1.25.3, processor/k8sattributesprocessor)	3m 26s
kubernetes-test-matrix (v1.25.3, receiver/kubeletstatsreceiver)	4m 25s
kubernetes-test-matrix (v1.25.3, receiver/k8sobjectsreceiver)	3m 40s
kubernetes-test-matrix (v1.24.7, receiver/k8sclusterreceiver)	5m 1s
kubernetes-test-matrix (v1.24.7, processor/k8sattributesprocessor)	3m 41s
kubernetes-test-matrix (v1.24.7, receiver/kubeletstatsreceiver)	4m 24s
kubernetes-test-matrix (v1.24.7, receiver/k8sobjectsreceiver)	3m 38s
kubernetes-test-matrix (v1.23.13, receiver/k8sclusterreceiver)	4m 59s
kubernetes-test-matrix (v1.23.13, processor/k8sattributesprocessor)	3m 29s
kubernetes-test-matrix (v1.23.13, receiver/kubeletstatsreceiver)	4m 36s
kubernetes-test-matrix (v1.23.13, receiver/k8sobjectsreceiver)	3m 36s
kubernetes-test	3s
	1h 17m 35s

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