Fix: Storage leak in Builder and Fetcher (#2979)

* Fix storage leak in builder
```
builder pod keeps old src and deployment packages irrespective of build status.
delete src package after every build request is completed.
delete deployment package after package is uploaded.
```
* Optimized src/deploy cleanup pkg code
* Fix high severity security issue
* Add a test for builder's Clean API
* Resolve review comments

---------

Signed-off-by: Md Soharab Ansari <soharab.ansari@infracloud.io>

cmd/builder/app/server.go

@@ -32,6 +32,7 @@ func Run(ctx context.Context, logger *zap.Logger, mgr manager.Interface, shareVo
 	builder := builder.MakeBuilder(logger, shareVolume)
 	mux := http.NewServeMux()
 	mux.HandleFunc("/", builder.Handler)
+	mux.HandleFunc("/clean", builder.Clean)
 	mux.HandleFunc("/version", builder.VersionHandler)
 	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusOK)