Revert "Make dotnet-watch tests TFM agnostic (#44604)"

This reverts commit 2d9a8cc.

Author: tmat

test/dotnet-watch.Tests/HotReload/ApplyDeltaTests.cs

@@ -249,8 +249,8 @@ class AppUpdateHandler
 
             await App.AssertOutputLineStartsWith("Updated");
 
-            AssertEx.ContainsRegex(
-                @"dotnet watch ⚠ \[WatchHotReloadApp \(net\d+\.\d+\)\] Expected to find a static method 'ClearCache' or 'UpdateApplication' on type 'AppUpdateHandler, WatchHotReloadApp, Version=1\.0\.0\.0, Culture=neutral, PublicKeyToken=null' but neither exists.",
+            AssertEx.Contains(
+                "dotnet watch ⚠ [WatchHotReloadApp (net9.0)] Expected to find a static method 'ClearCache' or 'UpdateApplication' on type 'AppUpdateHandler, WatchHotReloadApp, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' but neither exists.",
                 App.Process.Output);
         }
 
@@ -290,13 +290,13 @@ class AppUpdateHandler
 
             await App.AssertOutputLineStartsWith("Updated");
 
-            AssertEx.ContainsRegex(
-                @"dotnet watch ⚠ \[WatchHotReloadApp \(net\d+\.\d+\)\] Exception from 'System.Action`1\[System.Type\[\]\]': System.InvalidOperationException: Bug!",
+            AssertEx.Contains(
+                "dotnet watch ⚠ [WatchHotReloadApp (net9.0)] Exception from 'System.Action`1[System.Type[]]': System.InvalidOperationException: Bug!",
                 App.Process.Output);
 
             if (verbose)
             {
-                AssertEx.ContainsRegex(@"dotnet watch 🕵️ \[WatchHotReloadApp \(net\d+\.\d+\)\] Deltas applied.", App.Process.Output);
+                AssertEx.Contains("dotnet watch 🕵️ [WatchHotReloadApp (net9.0)] Deltas applied.", App.Process.Output);
             }
             else
             {

test/dotnet-watch.Tests/Utilities/AssertEx.cs

@@ -4,7 +4,6 @@
 #nullable disable
 
 using System.Collections;
-using System.Text.RegularExpressions;
 using Xunit.Sdk;
 
 namespace Microsoft.DotNet.Watch.UnitTests
@@ -247,26 +246,6 @@ public static void Contains(string expected, IEnumerable<string> items)
             Fail(message.ToString());
         }
 
-        public static void ContainsRegex(string pattern, IEnumerable<string> items)
-        {
-            var regex = new Regex(pattern, RegexOptions.Compiled);
-
-            if (items.Any(item => regex.IsMatch(item)))
-            {
-                return;
-            }
-
-            var message = new StringBuilder();
-            message.AppendLine($"Pattern '{pattern}' not found in:");
-
-            foreach (var item in items)
-            {
-                message.AppendLine($"'{item}'");
-            }
-
-            Fail(message.ToString());
-        }
-
         public static void DoesNotContain(string expected, IEnumerable<string> items)
             => Assert.DoesNotContain(expected, items);
     }