a11y tests: Double the timeout for UI tests

Increase the timeout for a11y UI tests from 1 to 2 min,
to see whether this helps with one slow Windows Jenkins
builder running into the timeout every once in a while,
as was mentioned in ESC calls.

Example from [1]:

    timeout waiting for dialog 'Bookmark' to show up
    warn:vcl.schedule:6600:11456:vcl/source/app/scheduler.cxx:524: Uncaught exception during Task::Invoke()!
    abort() has been calledwarn:sal.cppunittester:6600:11456:sal/cppunittester/cppunittester.cxx:601: CAUGHT SIGABRT:
    [...]

[1] https://ci.libreoffice.org/job/gerrit_windows/181051/console

Change-Id: I5b16ea8c538f6e2b5a30ebac714e177e696aac92
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/170569
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Tested-by: Jenkins

test/source/a11y/accessibletestbase.cxx

@@ -436,7 +436,7 @@ test::AccessibleTestBase::awaitDialog(const std::u16string_view name,
             mxToolkit->addTopWindowListener(mxTopWindowListener);
 
             maTimeoutTimer.SetInvokeHandler(LINK(this, ListenerHelper, timeoutTimerHandler));
-            maTimeoutTimer.SetTimeout(60000);
+            maTimeoutTimer.SetTimeout(120000);
             maTimeoutTimer.Start();
 
             maIdleHandler.SetInvokeHandler(LINK(this, ListenerHelper, idleHandler));