Use TryGetValue to prevent double lookup and also shorten code

Author: absurdlylongusername

src/Servers/IIS/IntegrationTesting.IIS/src/IISDeployer.cs

@@ -86,10 +86,9 @@ public override Task<DeploymentResult> DeployAsync()
             // For now, only support using published output
             DeploymentParameters.PublishApplicationBeforeDeployment = true;
             // Move ASPNETCORE_DETAILEDERRORS to web config env variables
-            if (IISDeploymentParameters.EnvironmentVariables.ContainsKey(DetailedErrorsEnvironmentVariable))
+            if (IISDeploymentParameters.EnvironmentVariables.TryGetValue(DetailedErrorsEnvironmentVariable, out var value))
             {
-                IISDeploymentParameters.WebConfigBasedEnvironmentVariables[DetailedErrorsEnvironmentVariable] =
-                    IISDeploymentParameters.EnvironmentVariables[DetailedErrorsEnvironmentVariable];
+                IISDeploymentParameters.WebConfigBasedEnvironmentVariables[DetailedErrorsEnvironmentVariable] = value;
 
                 IISDeploymentParameters.EnvironmentVariables.Remove(DetailedErrorsEnvironmentVariable);
             }