Always powerwash on channel change if arbitrary channel allowed.

Merged is_powerwash_allowed() and to_more_stable_channel() into
ShouldPowerwash().

Bug: 73082835
Test: update_engine_unittests
Change-Id: I6b7af0d1dac28d5fa9cddf4391bbd9cdf2acb57b
diff --git a/omaha_response_handler_action_unittest.cc b/omaha_response_handler_action_unittest.cc
index 4e9c03f..9e2cdd1 100644
--- a/omaha_response_handler_action_unittest.cc
+++ b/omaha_response_handler_action_unittest.cc
@@ -393,8 +393,7 @@
 #endif  // __ANDROID__
   EXPECT_TRUE(params.SetTargetChannel("stable-channel", true, nullptr));
   params.UpdateDownloadChannel();
-  EXPECT_TRUE(params.to_more_stable_channel());
-  EXPECT_TRUE(params.is_powerwash_allowed());
+  EXPECT_TRUE(params.ShouldPowerwash());
 
   fake_system_state_.set_request_params(&params);
   InstallPlan install_plan;
@@ -426,8 +425,7 @@
 #endif  // __ANDROID__
   EXPECT_TRUE(params.SetTargetChannel("canary-channel", false, nullptr));
   params.UpdateDownloadChannel();
-  EXPECT_FALSE(params.to_more_stable_channel());
-  EXPECT_FALSE(params.is_powerwash_allowed());
+  EXPECT_FALSE(params.ShouldPowerwash());
 
   fake_system_state_.set_request_params(&params);
   InstallPlan install_plan;