fix(xo-server/backup legacy/delta import): autofix path (#2941)

Because the path might be incorrect and be `_full.vhd` instead of `_delta.vhd`.

I know…

packages/xo-server/src/xo-mixins/backups.js

@@ -815,10 +815,17 @@ export default class {
 
       await Promise.all(
         mapToArray(delta.vdis, async (vdi, id) => {
-          streams[`${id}.vhd`] = await createVhdReadStream(
-            handler,
-            `${basePath}/${vdi.xoPath}`
-          )
+          let path = `${basePath}/${vdi.xoPath}`
+          try {
+            await handler.getSize(path)
+          } catch (error) {
+            if (error == null || error.code !== 'ENOENT') {
+              throw error
+            }
+
+            path = path.replace(/_delta\.vhd$/, '_full')
+          }
+          streams[`${id}.vhd`] = await createVhdReadStream(handler, path)
         })
       )