Rename aconfig intermediate file (json -> pb)

aconfig's intermediate file ("the cache") has changed format from json
to protobuf. Rename the generated file accordingly.

Bug: 283910447
Test: m nothing # run soong tests
Change-Id: Iaff408774cfba4231dfb951b112b554466b8e884
diff --git a/device_config/device_config_definitions.go b/device_config/device_config_definitions.go
index bb78695..ab2e4f7 100644
--- a/device_config/device_config_definitions.go
+++ b/device_config/device_config_definitions.go
@@ -122,7 +122,7 @@
 
 	// Intermediate format
 	inputFiles := android.PathsForModuleSrc(ctx, module.properties.Srcs)
-	intermediatePath := android.PathForModuleOut(ctx, "intermediate.json")
+	intermediatePath := android.PathForModuleOut(ctx, "intermediate.pb")
 	ctx.Build(pctx, android.BuildParams{
 		Rule:        aconfigRule,
 		Inputs:      inputFiles,