Apply suggestions from code review

Co-authored-by: Nikolaj Geisle <[email protected]>

Author: nikolajlauridsen

src/Umbraco.Tests.Common/Builders/ContentCultureInfosCollectionBuilder.cs

@@ -7,7 +7,7 @@ namespace Umbraco.Cms.Tests.Common.Builders
 {
     public class ContentCultureInfosCollectionBuilder : ChildBuilderBase<ContentBuilder, ContentCultureInfosCollection>, IBuildContentCultureInfosCollection
     {
-        private List<ContentCultureInfosBuilder> _cultureInfosBuilders;
+        private readonly List<ContentCultureInfosBuilder> _cultureInfosBuilders;
         public ContentCultureInfosCollectionBuilder(ContentBuilder parentBuilder) : base(parentBuilder) => _cultureInfosBuilders = new List<ContentCultureInfosBuilder>();
 
         public ContentCultureInfosBuilder AddCultureInfos()

src/Umbraco.Tests.Integration/Umbraco.Web.BackOffice/Controllers/ContentControllerTests.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Umbraco.
 // See LICENSE for more details.
 
-using System.Globalization;
 using System.Linq;
 using System.Net;
 using System.Net.Http;
@@ -440,12 +439,11 @@ public async Task PostSave_Validates_Domains_Exist()
             {
                 { new StringContent(JsonConvert.SerializeObject(model)), "contentItem" }
             });
+            
             var body = await response.Content.ReadAsStringAsync();
             body = body.TrimStart(AngularJsonMediaTypeFormatter.XsrfPrefix);
             ContentItemDisplay display = JsonConvert.DeserializeObject<ContentItemDisplay>(body);
 
-            var currentThreadCulture = Thread.CurrentThread.CurrentCulture.TwoLetterISOLanguageName;
-            var currentUICulture = Thread.CurrentThread.CurrentUICulture.TwoLetterISOLanguageName;
             ILocalizedTextService localizedTextService = GetRequiredService<ILocalizedTextService>();
             var expectedMessage = localizedTextService.Localize("speechBubbles", "publishWithNoDomains");