Fix cross-platform Phase 2 analyzers

Author: Arbousier1

tools/perf/analyze-phase2-abba.ps1

@@ -601,5 +601,5 @@ Write-JsonResult ([ordered]@{
     pairing = "adjacent positions 1-2 and 3-4 within each restart-per-run block"
     estimator = "exp(median(paired log(B/A)))"
     confidenceInterval = "deterministic paired bootstrap percentile 95% CI"
-    results = @($results)
+    results = @($results.ToArray())
 })

tools/perf/analyze-phase2-pcap.ps1

@@ -660,8 +660,8 @@ function Export-PcapFieldsCsv {
 
     & $tshark @arguments 2> $ErrorPath | Set-Content -LiteralPath $CsvPath -Encoding UTF8
     $exitCode = $LASTEXITCODE
-    $standardError = if (Test-Path -LiteralPath $ErrorPath) {
-        Get-Content -LiteralPath $ErrorPath -Raw -Encoding UTF8
+    [string]$standardError = if (Test-Path -LiteralPath $ErrorPath) {
+        [string](Get-Content -LiteralPath $ErrorPath -Raw -Encoding UTF8)
     } else { "" }
     if ($exitCode -ne 0) {
         throw "tshark field export failed (exit $exitCode): $standardError"