Quick ci fix (#3084)

The defensive flattening of the inputs was at the wrong place.

---

#### Does this PR need a docs update or release note?

- [ ] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [ ] ⛔ No

#### Type of change

<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [x] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Supportability/Tests
- [x] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

#### Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* #<issue>

#### Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

src/cmd/purge/scripts/onedrivePurge.ps1

@@ -112,10 +112,6 @@ function Purge-Library {
 
 ######## MAIN #########
 
-# ensure that there are no unexpanded entries in the list of parameters
-$LibraryNameList = $LibraryNameList | ForEach-Object { @($_.Split(',').Trim()) }
-$FolderPrefixPurgeList = $FolderPrefixPurgeList | ForEach-Object { @($_.Split(',').Trim()) }
-
 # Setup SharePointPnP
 if (-not (Get-Module -ListAvailable -Name PnP.PowerShell)) {
     $ProgressPreference = 'SilentlyContinue'
@@ -173,6 +169,10 @@ Write-Host "`nAuthenticating and connecting to $SiteUrl"
 Connect-PnPOnline -Url $siteUrl -Credential $cred
 Write-Host "Connected to $siteUrl`n"
 
+# ensure that there are no unexpanded entries in the list of parameters
+$LibraryNameList = $LibraryNameList | ForEach-Object { @($_.Split(',').Trim()) }
+$FolderPrefixPurgeList = $FolderPrefixPurgeList | ForEach-Object { @($_.Split(',').Trim()) }
+
 foreach ($library in $LibraryNameList) {
     Purge-Library -LibraryName $library -PurgeBeforeTimestamp $PurgeBeforeTimestamp -FolderPrefixPurgeList $FolderPrefixPurgeList -SiteSuffix $siteSiffix
 }