feature: disable proxy when config is empty (dragonflyoss#455)

Signed-off-by: Jim Ma <[email protected]>

Add e2e dfget test cases (dragonflyoss#450)

* test: rename e2e/util to e2e/e2eutil

Signed-off-by: Jim Ma <[email protected]>

* test: add dfget e2e test

Signed-off-by: Jim Ma <[email protected]>