Fix some migration and repo name problems (#33986)

1. Ignore empty inputs in `UnmarshalHandleDoubleEncode`
2. Ignore non-existing `stateEvent.User` in gitlab migration
3. Enable `release` and `wiki` units when they are selected in migration
4. Sanitize repo name for migration and new repo

services/doctor/fix16961_test.go

@@ -18,12 +18,6 @@ func Test_fixUnitConfig_16961(t *testing.T) {
 		wantFixed bool
 		wantErr   bool
 	}{
-		{
-			name:      "empty",
-			bs:        "",
-			wantFixed: true,
-			wantErr:   false,
-		},
 		{
 			name:      "normal: {}",
 			bs:        "{}",