[lldb][test][NFC] Narrow scope of import pexpect

We do not run `pexpect` based tests on Windows, but there are still cases where those tests run `import pexpect` outside of the scope where the test is skipped. By moving the import statement to a different scope, those tests can run even when `pexpect` truly isn't installed.

Tangentially related: TestSTTYBeforeAndAfter.py is using a manual `@expectedFailureAll` for windows instead of the common `@skipIfWindows`. If `pexepect` is generally expected to not be available, we should not bother running the test at all.

lldb/test/API/driver/quit_speed/TestQuitWithProcess.py

@@ -2,12 +2,10 @@
 Test that killing the target while quitting doesn't stall
 """
 
-
 import lldb
 from lldbsuite.test.decorators import *
 from lldbsuite.test.lldbtest import *
 from lldbsuite.test import lldbutil
-import pexpect
 from lldbsuite.test.lldbpexpect import PExpectTest
 
 
@@ -16,6 +14,8 @@ class DriverQuitSpeedTest(PExpectTest):
 
  def test_run_quit(self):
  """Test that the lldb driver's batch mode works correctly."""
+ import pexpect
+
  self.build()
 
  exe = self.getBuildArtifact("a.out")

lldb/test/API/functionalities/progress_reporting/TestTrimmedProgressReporting.py

@@ -3,7 +3,6 @@
 """
 
 import os
-import pexpect
 import tempfile
 import re
 

lldb/test/API/terminal/TestSTTYBeforeAndAfter.py

@@ -19,10 +19,7 @@ def classCleanup(cls):
  cls.RemoveTempFile("child_send2.txt")
  cls.RemoveTempFile("child_read2.txt")
 
- @expectedFailureAll(
- hostoslist=["windows"],
- bugnumber="llvm.org/pr22274: need a pexpect replacement for windows",
- )
+ @skipIfWindows # llvm.org/pr22274: need a pexpect replacement for windows
  @no_debug_info_test
  def test_stty_dash_a_before_and_afetr_invoking_lldb_command(self):
  """Test that 'stty -a' displays the same output before and after running the lldb command."""