[lldb/test] Fix PExpect.launch issue when disabling color support

This patch should fix a bug in PExpect.launch that happened when color
support is not enabled.

In that case, we need to add the `--no-use-colors` flag to lldb's launch
argument list. However, previously, each character to the string was
appended separately to the `args` list. This patch solves that by adding
the whole string to the list.

This should fix the TestIOHandlerResize failure on GreenDragon.

Differential Revision: https://reviews.llvm.org/D126021

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>

lldb/packages/Python/lldbsuite/test/lldbpexpect.py

@@ -34,7 +34,7 @@ class PExpectTest(TestBase):
             args += run_under
         args += [lldbtest_config.lldbExec, '--no-lldbinit']
         if not use_colors:
-            args += '--no-use-colors'
+            args.append('--no-use-colors')
         for cmd in self.setUpCommands():
             if "use-color false" in cmd and use_colors:
                 continue