Delete empty entries for covertedModules in bp2build_metrics

Test: `m nothing` and verify the bp2build_metrics
Bug: 257975713
Change-Id: Ib6b8a116bee20f3eef80cadaa0afac28a25e2121

bp2build/metrics.go

@@ -173,6 +173,10 @@ const (
 )
 
 func (metrics *CodegenMetrics) AddConvertedModule(m blueprint.Module, moduleType string, dir string, conversionType ConversionType) {
+	//a package module has empty name
+	if moduleType == "package" {
+		return
+	}
 	// Undo prebuilt_ module name prefix modifications
 	moduleName := android.RemoveOptionalPrebuiltPrefix(m.Name())
 	metrics.serialized.ConvertedModules = append(metrics.serialized.ConvertedModules, moduleName)