Two different images incorrectly have the same size despite being expected to differ

[Gary.Wang]

Steps to reproduce:
1. Bootstrap anbox cloud appliance locally
2. Launch an instance with the following command
   amc launch -r
   This caused the default image to be synced automatically for the first time and image version 0 was created.
3. Switch the image server to the nightly bucket
4. Wait a bit, a new image version(version 1) was added and synced to the ams automatically.
5. Check the image versions details with
   ```
   amc image show
   ```

Actual results:
Two different images with different remote id incorrectly have the same size despite being expected to differ