Tests | Address transient errors in CI pipelines (#4314)

* Retry installing dotnet in CI + address flaky tests

* One more flaky test

Author: cheenamalhotra

eng/pipelines/steps/install-dotnet.yml

@@ -57,8 +57,12 @@ steps:
   - ${{ if ne(parameters.architecture, 'arm64') }}:
 
     # Install the SDK listed in the global.json file.
+    #
+    # retryCountOnTaskFailure is set because UseDotNet@2 fails intermittently
+    # in CI due to transient network/CDN issues when downloading the SDK.
     - task: UseDotNet@2
       displayName: Install .NET SDK (global.json)
+      retryCountOnTaskFailure: 3
       inputs:
         installationPath: ${{ parameters.installDir }}
         packageType: sdk
@@ -71,6 +75,7 @@ steps:
     - ${{ each version in parameters.runtimes }}:
       - task: UseDotNet@2
         displayName: Install .NET ${{ version }} Runtime
+        retryCountOnTaskFailure: 3
         inputs:
           installationPath: ${{ parameters.installDir }}
           packageType: runtime
@@ -83,8 +88,13 @@ steps:
   - ${{ else }}:
 
     # Use the install script for ARM64.
+    #
+    # retryCountOnTaskFailure provides an outer retry around the script's
+    # internal retry loop, in case the script download itself or the entire
+    # step fails due to transient issues.
     - task: PowerShell@2
       displayName: Install .NET SDK and Runtimes for ARM64
+      retryCountOnTaskFailure: 3
       inputs:
         targetType: filePath
         pwsh: true

src/Microsoft.Data.SqlClient/tests/UnitTests/SimulatedServerTests/ConnectionFailoverTests.cs

@@ -389,6 +389,7 @@ public void TransientFault_ShouldConnectToPrimary(uint errorCode)
         [InlineData(40613)]
         [InlineData(42108)]
         [InlineData(42109)]
+        [Trait("Category", "flaky")]
         public void TransientFault_RetryDisabled_ShouldFail(uint errorCode)
         {
             // Arrange
@@ -484,6 +485,7 @@ public void TransientFault_WithUserProvidedPartner_ShouldConnectToPrimary(uint e
         [InlineData(40613)]
         [InlineData(42108)]
         [InlineData(42109)]
+        [Trait("Category", "flaky")]
         public void TransientFault_WithUserProvidedPartner_RetryDisabled_ShouldFail(uint errorCode)
         {
             // Arrange

src/Microsoft.Data.SqlClient/tests/UnitTests/SimulatedServerTests/ConnectionRoutingTestsAzure.cs

@@ -159,6 +159,7 @@ public void NetworkDelayAtRoutedLocation_RetryDisabled_ShouldSucceed()
         }
 
         [Fact]
+        [Trait("Category", "flaky")]
         public void NetworkTimeoutAtRoutedLocation_RetryDisabled_ShouldFail()
         {
             // Arrange