[flutter_tools] exit script if powershell version detection fails (#64773)

bin/internal/shared.bat

@@ -92,7 +92,13 @@ GOTO :after_subroutine
     SET update_dart_bin=%FLUTTER_ROOT%/bin/internal/update_dart_sdk.ps1
     REM Escape apostrophes from the executable path
     SET "update_dart_bin=!update_dart_bin:'=''!"
-    %powershell_executable% -ExecutionPolicy Bypass -Command "Unblock-File -Path '%update_dart_bin%'; & '%update_dart_bin%'"
+    REM PowerShell command must have exit code set in order to prevent all non-zero exit codes from being translated
+    REM into 1. The exit code 2 is used to detect the case where the major version is incorrect and there should be
+    REM no subsequent retries.
+    %powershell_executable% -ExecutionPolicy Bypass -Command "Unblock-File -Path '%update_dart_bin%'; & '%update_dart_bin%'; exit $LASTEXITCODE;"
+    IF "%ERRORLEVEL%" EQU "2" (
+      EXIT 1
+    )
     IF "%ERRORLEVEL%" NEQ "0" (
       ECHO Error: Unable to update Dart SDK. Retrying...
       timeout /t 5 /nobreak

bin/internal/update_dart_sdk.ps1

@@ -29,7 +29,9 @@ $psMajorVersionLocal = $PSVersionTable.PSVersion.Major
 if ($psMajorVersionLocal -lt $psMajorVersionRequired) {
     Write-Host "Flutter requires PowerShell $psMajorVersionRequired.0 or newer."
     Write-Host "See https://flutter.dev/docs/get-started/install/windows for more."
-    return
+    Write-Host "Current version is $psMajorVersionLocal."
+    # Use exit code 2 to signal that shared.bat should exit immediately instead of retrying.
+    exit 2
 }
 
 if ((Test-Path $engineStamp) -and ($engineVersion -eq (Get-Content $engineStamp))) {