Remove "Test" prop from xx_aconfig_library build rules

Test: CI

Bug: 309990433
Change-Id: Id78f65d4083571f310686589a18cabe13bbd5d62

aconfig/rust_aconfig_library_test.go

@@ -119,8 +119,6 @@ var incorrectRustCodegenModeTestData = []struct {
 	setting, expectedErr string
 }{
 	{"mode: `unsupported`,", "mode: \"unsupported\" is not a supported mode"},
-	// TODO: remove this test case when test prop is removed
-	{"mode: `test`, test: true", "test prop should not be specified when mode prop is set"},
 }
 
 func TestIncorrectRustCodegenMode(t *testing.T) {