Fix non determinism in prebuilt_* modules generation

Ensures that the generated modules' properties are deterministic by
iterating the map in a sorted manner.

Test: m nothing
Bug: 378760592
Change-Id: Ibe6fd753372e65ddda30f12201747d88421165fd
diff --git a/fsgen/prebuilt_etc_modules_gen.go b/fsgen/prebuilt_etc_modules_gen.go
index 73fb8d7..97d5482 100644
--- a/fsgen/prebuilt_etc_modules_gen.go
+++ b/fsgen/prebuilt_etc_modules_gen.go
@@ -279,7 +279,8 @@
 
 	for fileIndex := range maxLen {
 		srcTuple := []srcBaseFileInstallBaseFileTuple{}
-		for _, groupedDestFile := range groupedDestFiles {
+		for _, srcFile := range android.SortedKeys(groupedDestFiles) {
+			groupedDestFile := groupedDestFiles[srcFile]
 			if len(groupedDestFile) > fileIndex {
 				srcTuple = append(srcTuple, groupedDestFile[fileIndex])
 			}