Add warning message to old unused package (#2064)

The original way of reading *.json under `PackageInfo` is not working at the case which artifact is under ci.yml but old mgmt which is not used anymore.
The PR is to skip the old unused package and throw warning message.

The test pipeline:
https://dev.azure.com/azure-sdk/internal/_build/results?buildId=1127833&view=results

eng/common/pipelines/templates/steps/update-docsms-metadata.yml

@@ -75,7 +75,7 @@ steps:
       DefaultBranchVariableName: TargetBranchName
 
 - pwsh: |
-    $packageInfoJson = '${{ convertToJson(parameters.PackageInfoLocations) }}'.Trim('"')
+    $packageInfoJson = '${{ convertToJson(parameters.PackageInfoLocations) }}'.Trim('"').Replace("\\", "/")
     $packageInfoLocations = ConvertFrom-Json $packageInfoJson
     ${{ parameters.ScriptDirectory }}/Update-DocsMsMetadata.ps1 `
       -PackageInfoJsonLocations $packageInfoLocations `

eng/common/scripts/Update-DocsMsMetadata.ps1

@@ -62,6 +62,7 @@ function GetAdjustedReadmeContent($ReadmeContent, $PackageInfo, $PackageMetadata
 
   # Generate the release tag for use in link substitution
   $tag = "$($PackageInfo.Name)_$($PackageInfo.Version)"
+  Write-Host "The tag of package: $tag"
   $date = Get-Date -Format "MM/dd/yyyy"
 
 
@@ -97,9 +98,13 @@ ms.service: $service
 }
 
 function UpdateDocsMsMetadataForPackage($packageInfoJsonLocation) { 
+  if (!(Test-Path $packageInfoJsonLocation)) {
+    LogWarning "Package metadata not found for $packageInfoJsonLocation"
+    return
+  }
+
   $packageInfoJson = Get-Content $packageInfoJsonLocation -Raw
   $packageInfo = ConvertFrom-Json $packageInfoJson
-
   $originalVersion = [AzureEngSemanticVersion]::ParseVersionString($packageInfo.Version)
   if ($packageInfo.DevVersion) {
     # If the package is of a dev version there may be language-specific needs to