Fix retry when downloading clang tools

Invoke-WebRequest throws an exception when the download fails, so we
should use try-catch instead of status code to check failure.

In addition pass -PassThru to avoid leaving a corrupted download file in
case the download fails. This will buffer the download and write it once
at the end.

Fix dotnet#57196

eng/formatting/download-tools.ps1

@@ -1,6 +1,5 @@
 
-function DownloadClangTool
-{
+function DownloadClangTool {
     param (
         [string]
         $toolName,
@@ -10,27 +9,28 @@ function DownloadClangTool
 
     $baseUri = "https://clrjit.blob.core.windows.net/clang-tools/windows"
 
-    if (-not $(ls $downloadOutputPath | Where-Object {$_.Name -eq "$toolName.exe"}))
-    {
+    if (-not $(ls $downloadOutputPath | Where-Object { $_.Name -eq "$toolName.exe" })) {
         $baseBackoffSeconds = 2;
 
         $success = $false
         for ($i = 0; $i -lt 5; $i++) {
-            echo "Attempting download of '$baseUri/$toolName.exe'"
-            $status = Invoke-WebRequest -Uri "$baseUri/$toolName.exe" -OutFile $(Join-Path $downloadOutputPath -ChildPath "$toolName.exe")
-            if ($status.StatusCode -lt 400)
-            {
+            Write-Output "Attempting download of '$baseUri/$toolName.exe'"
+            try {
+                # Pass -PassThru as otherwise Invoke-WebRequest leaves a corrupted file if the download fails. With -PassThru the download is buffered first.
+                $null = Invoke-WebRequest -Uri "$baseUri/$toolName.exe" -OutFile $(Join-Path $downloadOutputPath -ChildPath "$toolName.exe") -PassThru
                 $success = $true
                 break
-            } else {
-                echo "Download attempt $($i+1) failed. Trying again in $($baseBackoffSeconds + $baseBackoffSeconds * $i) seconds"
-                Start-Sleep -Seconds $($baseBackoffSeconds + $baseBackoffSeconds * $i)
             }
+            catch {
+                Write-Output $_
+            }
+
+            Write-Output "Download attempt $($i+1) failed. Trying again in $($baseBackoffSeconds + $baseBackoffSeconds * $i) seconds"
+            Start-Sleep -Seconds $($baseBackoffSeconds + $baseBackoffSeconds * $i)
         }
-        if (-not $success)
-        {
-            Write-Output "Failed to download clang-format"
-            return 1
+        if (-not $success) {
+            Write-Output "Failed to download $toolName"
+            throw [System.IO.IOException] "Could not download $toolName"
         }
     }
 }