Try bumping foundation tests to 8 jobs

Author: bnbarham

utils/build.ps1

@@ -2850,8 +2850,10 @@ function Test-Foundation {
     -Src $SourceCache\swift-foundation `
     -Bin "$ScratchPath" `
     -Platform $BuildPlatform `
+    -Configuration $FoundationTestConfiguration `
     --multiroot-data-file "$SourceCache\swift\utils\build_swift\resources\SwiftPM-Unified-Build.xcworkspace" `
-    --test-product swift-foundationPackageTests
+    --test-product swift-foundationPackageTests `
+    -j 2 # Running too parallel causes a non-deterministic crash in CI only, see https://github.com/swiftlang/swift/issues/83606
 
   Invoke-IsolatingEnvVars {
     $env:DISPATCH_INCLUDE_PATH="$(Get-SwiftSDK $BuildPlatform.OS)/usr/include"
@@ -2865,8 +2867,10 @@ function Test-Foundation {
       -Src $SourceCache\swift-corelibs-foundation `
       -Bin "$ScratchPath" `
       -Platform $BuildPlatform `
+      -Configuration $FoundationTestConfiguration `
       --multiroot-data-file "$SourceCache\swift\utils\build_swift\resources\SwiftPM-Unified-Build.xcworkspace" `
-      --test-product swift-corelibs-foundationPackageTests
+      --test-product swift-corelibs-foundationPackageTests `
+      -j 2 # Running too parallel causes a non-deterministic crash in CI only, see https://github.com/swiftlang/swift/issues/83606
   }
 }