message: Simplify TestGdbRemoteRegisterState
  While reviewing D56233 it became clear to me that this test can be
  simplified. There's no need for a start-stop cycle in the inferior -- we
  can start fiddling with its registers as soon as it is launched.
diff: @@ -24,15 +24,6 @@ class TestGdbRemoteRegisterState(gdbremote_testcase.GdbRemoteTestCaseBase):
  if with_suffix:
  self.add_thread_suffix_request_packets()
  self.add_threadinfo_collection_packets()
  - self.test_sequence.add_log_lines([
  - # Start the inferior...
  - "read packet: $c#63",
  - # ... match output....
  - {"type": "output_match", "regex": self.maybe_strict_output_regex(
  - r"message:main entered\r\n")},
  - ], True)
  - # ... then interrupt.
  - self.add_interrupt_packets()
  context = self.expect_gdbremote_sequence()
  self.assertIsNotNone(context)
  