include symlink metrics in bp2build_metrics.pb

Bug: b/256212479
Test: Prior to thi CL bp2build.symlink_forest event was missing in bp2build_metrics.pb after a clean mixed build
Change-Id: I53bfc4114a383c0d1f9c4c7945e7d4c69bc50b0c
diff --git a/bp2build/build_conversion.go b/bp2build/build_conversion.go
index 82ce115..a06b89e 100644
--- a/bp2build/build_conversion.go
+++ b/bp2build/build_conversion.go
@@ -28,7 +28,6 @@
 	"android/soong/android"
 	"android/soong/bazel"
 	"android/soong/starlark_fmt"
-
 	"github.com/google/blueprint"
 	"github.com/google/blueprint/proptools"
 )
@@ -245,12 +244,7 @@
 	buildFileToTargets := make(map[string]BazelTargets)
 
 	// Simple metrics tracking for bp2build
-	metrics := CodegenMetrics{
-		ruleClassCount:           make(map[string]uint64),
-		convertedModulePathMap:   make(map[string]string),
-		convertedModuleTypeCount: make(map[string]uint64),
-		totalModuleTypeCount:     make(map[string]uint64),
-	}
+	metrics := CreateCodegenMetrics()
 
 	dirs := make(map[string]bool)