Revert "add rust_toolchain_rustc_prebuilt module type"

Revert submission 2605644-rulebuilder-ninja-vars

Reason for revert: b/299568218

Reverted changes: /q/submissionid:2605644-rulebuilder-ninja-vars

Change-Id: Ic3d1ba7e8a61427b52f31cc3f187c9d5a7d9a7bb
diff --git a/android/prebuilt_build_tool.go b/android/prebuilt_build_tool.go
index 17b3230..aeae20f 100644
--- a/android/prebuilt_build_tool.go
+++ b/android/prebuilt_build_tool.go
@@ -17,7 +17,7 @@
 import "path/filepath"
 
 func init() {
-	RegisterModuleType("prebuilt_build_tool", NewPrebuiltBuildTool)
+	RegisterModuleType("prebuilt_build_tool", prebuiltBuildToolFactory)
 }
 
 type prebuiltBuildToolProperties struct {
@@ -101,6 +101,10 @@
 
 // prebuilt_build_tool is to declare prebuilts to be used during the build, particularly for use
 // in genrules with the "tools" property.
+func prebuiltBuildToolFactory() Module {
+	return NewPrebuiltBuildTool()
+}
+
 func NewPrebuiltBuildTool() Module {
 	module := &prebuiltBuildTool{}
 	module.AddProperties(&module.properties)