Address various linter (staticcheck, modernize, etc.) comments.

Additionally, fix bug to properly identify dynamically created group
snapshots for fixed group snapshot content names when group snapshots
are being deleted.

Author: grant-he

cmd/snapshot-controller/main.go

@@ -335,6 +335,6 @@ func buildConfig(kubeconfig string) (*rest.Config, error) {
 
 type promklog struct{}
 
-func (pl promklog) Println(v ...interface{}) {
+func (pl promklog) Println(v ...any) {
 	klog.Error(v...)
 }