Add retry logic to prerequisite URL tests (#5601)

* Disable Requisiste URLs tests

* Add retry for the URL tests

test/powershell/Installer/WindowsInstaller.Tests.ps1

@@ -15,10 +15,21 @@ Describe "Windows Installer" -Tags "Scenario" {
         (Get-Content $wixProductFile -Raw).Contains($preRequisitesLink) | Should Be $true
     }
 
-    It "Pre-Requisistes link for '<Name>' is reachable: <url>" -TestCases $linkCheckTestCases -Test {
+    ## Running 'Invoke-WebRequest' with WMF download URLs has been failing intermittently,
+    ## because sometimes the URLs lead to a 'this download is no longer available' page.
+    ## We use a retry logic here. Retry for 5 times with 1 second interval.
+    It "Pre-Requisistes link for '<Name>' is reachable: <url>" -TestCases $linkCheckTestCases {
         param ($Url)
 
-        # Because an outdated link 'https://www.microsoft.com/download/details.aspx?id=504100000' would still return a 200 reponse (due to a redirection to an error page), it only checks that it returns something
-        (Invoke-WebRequest $Url -UseBasicParsing) | Should Not Be $null
+        foreach ($i in 1..5) {
+            try {
+                $result = Invoke-WebRequest $Url -UseBasicParsing
+                break;
+            } catch {
+                Start-Sleep -Seconds 1
+            }
+        }
+
+        $result | Should Not Be $null
     }
 }