[lldb/testsuite] Change get_debugserver_exe to support Rosetta

In order to be able to run the debugserver tests against the Rosetta
debugserver, detect the Rosetta run configuration and return the
system Rosetta debugserver.

(cherry picked from commit 99298c7)

Author: fredriss

lldb/packages/Python/lldbsuite/test/tools/lldb-server/lldbgdbserverutils.py

@@ -12,6 +12,7 @@
 import socket_packet_pump
 import subprocess
 from lldbsuite.test.lldbtest import *
+from lldbsuite.test import configuration
 
 from six.moves import queue
 
@@ -89,6 +90,10 @@ def get_debugserver_exe():
     if "LLDB_DEBUGSERVER_PATH" in os.environ:
         return os.environ["LLDB_DEBUGSERVER_PATH"]
 
+    if configuration.arch and configuration.arch == "x86_64" and \
+       platform.machine().startswith("arm64"):
+        return '/Library/Apple/usr/libexec/oah/debugserver'
+
     return _get_debug_monitor_from_lldb(
         lldbtest_config.lldbExec, "debugserver")