Allow to ignore duration in tests

There are other ways to adjust this value, but sometimes
it is just easier to just let test run.

tmt/steps/execute/__init__.py

@@ -261,6 +261,12 @@ class ExecuteStepData(tmt.steps.WhereableStepData, tmt.steps.StepData):
         option='--duration',
         help='The maximal time allowed for the test to run.',
     )
+    ignore_duration: bool = field(
+        default=False,
+        option=('--ignore-duration'),
+        is_flag=True,
+        help='Ignore test duration values and allow tests run forever.',
+    )
     exit_first: bool = field(
         default=False,
         option=('-x', '--exit-first'),
@@ -709,6 +715,7 @@ def go(
         logger: tmt.log.Logger,
     ) -> None:
         self.go_prolog(logger)
+        logger.verbose('ignore-duration', self.data.exit_first, 'green', level=2)
         logger.verbose('exit-first', self.data.exit_first, 'green', level=2)
 
     @property

tmt/steps/execute/internal.py

@@ -560,6 +560,10 @@ def _save_process(
 
                 timeout = None
 
+            elif self.data.ignore_duration:
+                logger.debug("Test duration is not effective due ignore-duration option.")
+                timeout = None
+
             else:
                 timeout = tmt.utils.duration_to_seconds(
                     test.duration, tmt.base.DEFAULT_TEST_DURATION_L1