Fix test issue of GerritCommonTest

The class PRED_get_legacy_label_types_1 of I414e62503
require GerritCommonTest prepare a ChangeControl object for
PrologEnvironment, else [1] will be failed. This commit
get it done.

[1] buck test //gerrit-server:prolog_tests

Change-Id: Id12dbec23a71d3bea744b738a48616c18213c241
3 files changed