tests/functional: Remove sleep() kludges from microblaze tests

Commit f0ec14c78c4 ("tests/avocado: Fix console data loss") fixed
QEMUMachine's problem with console, we don't need to use the sleep()
kludges.

Suggested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250206131052.30207-15-philmd@linaro.org>

tests/functional/test_microblazeel_s3adsp1800.py

@@ -7,8 +7,7 @@
 # This work is licensed under the terms of the GNU GPL, version 2 or
 # later. See the COPYING file in the top-level directory.
 
-import time
-from qemu_test import exec_command, exec_command_and_wait_for_pattern
+from qemu_test import exec_command_and_wait_for_pattern
 from qemu_test import QemuSystemTest, Asset
 from qemu_test import wait_for_console_pattern
 
@@ -31,9 +30,8 @@ def do_xmaton_le_test(self, machine):
         self.vm.add_args('-nic', f'user,tftp={tftproot}')
         self.vm.launch()
         wait_for_console_pattern(self, 'QEMU Advent Calendar 2023')
-        time.sleep(0.1)
-        exec_command(self, 'root')
-        time.sleep(0.1)
+        wait_for_console_pattern(self, 'buildroot login:')
+        exec_command_and_wait_for_pattern(self, 'root', '#')
         exec_command_and_wait_for_pattern(self,
                 'tftp -g -r xmaton.png 10.0.2.2 ; md5sum xmaton.png',
                 '821cd3cab8efd16ad6ee5acc3642a8ea')