Disable CS1591 on new tests

Author: edwardneal

src/Microsoft.Data.SqlClient/tests/UnitTests/UserAgentInfoTests.cs

@@ -26,6 +26,7 @@ namespace Microsoft.Data.SqlClient.UnitTests
     /// </summary>
     public class UserAgentInfoTests
     {
+#pragma warning disable CS1591 // Test classes do not require XML documentation comments
         // Cached payload is within the 2,047‑byte spec and never null
         [Fact]
         public void CachedPayload_IsNotNull_And_WithinSpecLimit()
@@ -70,6 +71,7 @@ public void TruncateOrDefault_Behaviour(string? input, int max, string expected)
             string actual = UserAgentInfo.TruncateOrDefault(input, max);
             Assert.Equal(expected, actual);
         }
+#pragma warning restore CS1591
 
         // AdjustJsonPayloadSize drops all low‑priority fields when required
 
@@ -295,6 +297,7 @@ public void Dto_JsonPropertyNames_MatchConstants(
             }
         }
 
+#pragma warning disable CS1591 // Test classes do not require XML documentation comments
         // End-to-end test that combines truncation, adjustment, and serialization
         [Fact]
         public void EndToEnd_Truncate_Adjust_Serialize_Works()
@@ -327,5 +330,6 @@ public void EndToEnd_Truncate_Adjust_Serialize_Works()
             JsonElement os = root.GetProperty(UserAgentInfoDto.OsJsonKey);
             Assert.Equal(osType, os.GetProperty(UserAgentInfoDto.OsInfo.TypeJsonKey).GetString());
         }
+#pragma warning restore CS1591
     }
 }