sys/internal/counters/activity APIs are inconsistent about rendering activity log info with invalid mount_accessor data

[maxb]

Activity log entries contain a mount_accessor field.

It can be missing, either because pre-1.10 Vault didn't write it at all, or because of bugs such as that mentioned in #18809. It could also be present but pointing at a deleted mount.

Some parts of the activity log code account for this:

vault/vault/activity_log.go

Lines 2341 to 2361 in 3ded138

	for mountAccessor, mountData := range nsMap[nsID].Mounts {
	var displayPath string
	if mountAccessor == "" {
	displayPath = "no mount accessor (pre-1.10 upgrade?)"
	} else {
	valResp := a.core.router.ValidateMountByAccessor(mountAccessor)
	if valResp == nil {
	displayPath = fmt.Sprintf("deleted mount; accessor %q", mountAccessor)
	} else {
	displayPath = valResp.MountPath
	}
	}
	mountRecord = append(mountRecord, &activity.MountRecord{
	MountPath: displayPath,
	Counts: &activity.CountsRecord{
	EntityClients: len(mountData.Counts.Entities),
	NonEntityClients: int(mountData.Counts.Tokens) + len(mountData.Counts.NonEntities),
	},
	})
	}

Other parts just throw data away if they don't successfully resolve a mount:

vault/vault/activity_log.go

Lines 2169 to 2173 in 3ded138

	valResp := a.core.router.ValidateMountByAccessor(mountAccessor)
	if valResp == nil {
	// Only persist valid mounts
	continue
	}

Which is incredibly confusing for users, when different parts of the JSON returned by Vault tell different stories about actual activity!