[Backport 7.58.x] Fix memory leak caused by container check (#29355)

Co-authored-by: sblumenthal <steven.blumenthal@datadoghq.com>

pkg/collector/corechecks/containers/generic/processor_network.go

@@ -87,6 +87,7 @@ func (pn *ProcessorNetwork) processGroupedContainerNetwork() {
 	for _, containerNetwork := range pn.ungroupedContainerNetwork {
 		pn.generateNetworkMetrics(containerNetwork.tags, containerNetwork.stats)
 	}
+	pn.ungroupedContainerNetwork = nil
 
 	for _, containerNetworks := range pn.groupedContainerNetwork {
 		// If we have multiple containers, tagging with container tag is incorrect as the metrics refer to whole isolation group.

releasenotes/notes/fix-container-check-memleak-d9ff028d5499197c.yaml

@@ -0,0 +1,11 @@
+# Each section from every release note are combined when the
+# CHANGELOG.rst is rendered. So the text needs to be worded so that
+# it does not depend on any information only available in another
+# section. This may mean repeating some details, but each section
+# must be readable independently of the other.
+#
+# Each section note must be formatted as reStructuredText.
+---
+fixes:
+  - |
+    Fixes memory leak caused by container check.