Revert "refactor(asset-proxy): encode url request to external source"

This reverts commit ffb79ba.

__tests__/asset-proxy.ts

@@ -28,7 +28,7 @@ test('request to https://asset-proxy.serlo.org/src?url=* gets asset from url que
   const env = currentTestEnvironment()
   const response = await env.fetch({
     subdomain: 'asset-proxy',
-    pathname: `/src?url=${encodeURIComponent('https://whatever.org/image')}`,
+    pathname: '/src?url=https://whatever.org/image',
   })
   expect(response.status).toBe(200)
   expect(response.headers.get('content-type')).toBe('image/png')

src/asset-proxy.ts

@@ -18,12 +18,9 @@ export async function assetProxy(request: Request): Promise<Response | null> {
     return getPlaceholder()
   }
 
-  const originalResponse = await fetch(
-    encodeURIComponent(assetUrl.toString()),
-    {
-      cf: { cacheTtl: 24 * 60 * 60 },
-    },
-  )
+  const originalResponse = await fetch(assetUrl, {
+    cf: { cacheTtl: 24 * 60 * 60 },
+  })
 
   if (originalResponse.ok && isImageResponse(originalResponse)) {
     const response = new Response(originalResponse.body, originalResponse)