Revert "Ignoring backspace for empty lines on stdin/stdout mode (#8196)" (#8239)

This reverts commit b525b1f0bd.

src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHostUserInterface.cs

@@ -1365,14 +1365,7 @@ namespace Microsoft.PowerShell
                 }
 
                 var c = unchecked((char)inC);
-                if (c == '\b' && !NoPrompt && sb.Length == 0)
-                {
-                    continue;
-                }
-                if (!NoPrompt)
-                {
-                    Console.Out.Write(c);
-                }
+                if (!NoPrompt) Console.Out.Write(c);
 
                 if (c == '\r')
                 {

test/powershell/Host/ConsoleHost.Tests.ps1

@@ -476,18 +476,6 @@ foo
             $process.StandardOutput.ReadToEnd() | Should -Be "PS> "
             EnsureChildHasExited $process
         }
-
-        It "Redirected input and sending backspace" {
-            # This test is for issue #8193, in which a backspace at the beginning of a command crashes powershell
-            $si = NewProcessStartInfo "-noprofile -nologo" -RedirectStdIn
-            $process = RunPowerShell $si
-            $process.StandardInput.Write("`$function:prompt = { 'PS> ' }`n")
-            $null = $process.StandardOutput.ReadLine()
-            $process.StandardInput.Write("`bexit`n")
-            $process.StandardOutput.ReadLine() | Should -Be "PS> exit"
-            $process.StandardInput.Close()
-            EnsureChildHasExited $process
-        }
     }
 
     Context "Exception handling" {