increase waiting timeout from 5/10 to 30 seconds

[bdrung]

Some tests run into the waiting timeout on the slow and emulated riscv64 architecture, for example:

=================================== FAILURES ===================================
__________________________ T.test_crash_system_slice ___________________________

self = <tests.system.test_signal_crashes.T testMethod=test_crash_system_slice>

    @unittest.skipIf(
        get_init_system() != "systemd", "running init system is not systemd"
    )
    @skip_if_command_is_missing("systemd-run")
    @unittest.skipIf(os.geteuid() != 0, "this test needs to be run as root")
    def test_crash_system_slice(self) -> None:
        """Report generation for a protected process running in the system
        slice"""
        apport.fileutils.report_dir = self.orig_report_dir
        self.test_report = os.path.join(
            apport.fileutils.report_dir,
            f"{self.TEST_EXECUTABLE.replace('/', '_')}.{os.getuid()}.crash",
        )

        system_run = self.create_test_process(
            command="/usr/bin/systemd-run",
            args=[
                "-t",
                "-q",
                "--slice=system.slice",
                "-p",
                "ProtectSystem=true",
                self.TEST_EXECUTABLE,
            ]
            + self.TEST_ARGS,
        )
        try:
            sleep_pid = wait_for_process_to_appear(
                self.TEST_EXECUTABLE, self.running_test_executables
            )
            wait_for_sleeping_state(sleep_pid)
            os.kill(sleep_pid, signal.SIGSEGV)

>           self.wait_for_no_instance_running(self.TEST_EXECUTABLE)

/tmp/autopkgtest.RQrDHF/autopkgtest_tmp/tests/system/test_signal_crashes.py:261:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
/tmp/autopkgtest.RQrDHF/autopkgtest_tmp/tests/system/test_signal_crashes.py:350: in wait_for_no_instance_running
    self.fail(f"Timeout exceeded, but {program} is still running.")
E   AssertionError: Timeout exceeded, but /usr/bin/gnusleep is still running.

So increase the waiting timeout from 5 and 10 seconds to 30 seconds.

There are multiple waiting functions but all have different conditions to wait for. Therefore is no easy way to unify them (while keeping them simple).

This PR should wait for #640 to land.

Bug: https://launchpad.net/bugs/2159030

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.49%. Comparing base (8a05b45) to head (5dbbcec).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #635   +/-   ##
=======================================
  Coverage   84.48%   84.49%           
=======================================
  Files         106      106           
  Lines       21014    21016    +2     
  Branches     3195     3195           
=======================================
+ Hits        17754    17757    +3     
  Misses       2785     2785           
+ Partials      475      474    -1     

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[bdrung]

Rebased.