Avoid errors from scraping filesystem metrics from unaccessible mounts

[dmitryax]

By excluding mount points that are not mounted to the collector container. Otherwise, the collector throws scraping errors:

2024-11-22T23:00:50.713Z	error	scraperhelper/scrapercontroller.go:204	Error scraping metrics	{"kind": "receiver", "name": "hostmetrics", "data_type": "metrics", "error": "failed to read usage at /hostfs/var/lib/kubelet/pods/5aee49ed-ddba-4277-a1e0-38eb528de562/volume-subpaths/config/configfile/1: no such file or directory; failed to read usage at /hostfs/var/lib/kubelet/pods/5aee49ed-ddba-4277-a1e0-38eb528de562/volume-subpaths/config-emptydir/opensearch/0: no such file or directory", "scraper": "filesystem"}
go.opentelemetry.io/collector/receiver/scraperhelper.(*controller).scrapeMetricsAndReport
	go.opentelemetry.io/collector/[email protected]/scraperhelper/scrapercontroller.go:204
go.opentelemetry.io/collector/receiver/scraperhelper.(*controller).startScraping.func1
	go.opentelemetry.io/collector/[email protected]/scraperhelper/scrapercontroller.go:180