Change file existence check in GxHttpClientTest

Updated file existence assertion to use GxContext.StaticPhysicalPath.

Author: claudiamurialdo

dotnet/test/DotNetUnitTest/Domain/GxHttpClientTest.cs

@@ -198,7 +198,7 @@ public void ToRelativeFile()
 				client.BaseURL = "/dummy/lem.txt";
 				client.Execute("GET", string.Empty);
 				client.ToFile("./lem.txt");
-				Assert.True(File.Exists(Path.Combine(Directory.GetCurrentDirectory(), "lem.txt")));
+				Assert.True(File.Exists(Path.Combine(GxContext.StaticPhysicalPath(), "lem.txt")), $"HttpClient.ToFile failed to create the file at path: {GxContext.StaticPhysicalPath()}");
 			}
 		}