Pipeline services assume event payload to be Dictionary

Pipeline services such as monitor and scheduler are based on PubSub events published on `node` channel.
While parsing event data, the services assume it to be a `Dict` and post-process data accordingly.

Previously, event payload data was [Dict](https://github.com/kernelci/kernelci-api/commit/7cd15778d6194e07c74f8e46e90d2ba80a5dc936) and hence the the pipeline services were implemented like that. But now it has changed to be [Any](https://github.com/kernelci/kernelci-api/commit/5764b7abadd1a627f8ccb07bd2ad6bf4a3e0ce9e) type. Thus, the issue with data post-processing in the pipeline has surfaced.

e.g. take a look at the below code section of monitor service:
```
event = self._api.receive_event(sub_id)
obj = event.data
dt = datetime.datetime.fromisoformat(event['time'])
commit = (obj['data']['kernel_revision']['commit'][:12]
if 'kernel_revision' in obj['data']
else str(None))
```

If somehow, `str` data is sent to `node` channel, it will end up in error.

Monitor service failure:
```
today at 12:11:55 File "/home/kernelci/pipeline/base.py", line 69, in run
today at 12:11:55 status = self._run(context)
today at 12:11:55 ^^^^^^^^^^^^^^^^^^
today at 12:11:55 File "/home/kernelci/./pipeline/monitor.py", line 64, in _run
today at 12:11:55 if 'kernel_revision' in obj['data']
today at 12:11:55 ~~~^^^^^^^^
today at 12:11:55TypeError: string indices must be integers, not 'str'
today at 12:11:55
today at 12:11:55Container stopped
```

Also, scheduler service with `shell` runtime:
```
today at 12:11:5503/18/2024 06:41:55 AM UTC [ERROR] Traceback (most recent call last):
today at 12:11:55 File "/home/kernelci/pipeline/base.py", line 69, in run
today at 12:11:55 status = self._run(context)
today at 12:11:55 ^^^^^^^^^^^^^^^^^^
today at 12:11:55 File "/home/kernelci/./pipeline/scheduler.py", line 189, in _run
today at 12:11:55 for job, runtime, platform, rules in self._sched.get_schedule(event):
today at 12:11:55 File "/usr/local/lib/python3.11/site-packages/kernelci/scheduler.py", line 44, in get_schedule
today at 12:11:55 for config in self.get_configs(event, channel):
today at 12:11:55 File "/usr/local/lib/python3.11/site-packages/kernelci/scheduler.py", line 39, in get_configs
today at 12:11:55 if sched_event.items() <= event.items():
today at 12:11:55 ^^^^^^^^^^^
today at 12:11:55AttributeError: 'str' object has no attribute 'items'
```

Scheduler with `docker`:
```
today at 12:11:5503/18/2024 06:41:55 AM UTC [ERROR] Traceback (most recent call last):
today at 12:11:55 File "/home/kernelci/pipeline/base.py", line 69, in run
today at 12:11:55 status = self._run(context)
today at 12:11:55 ^^^^^^^^^^^^^^^^^^
today at 12:11:55 File "/home/kernelci/./pipeline/scheduler.py", line 189, in _run
today at 12:11:55 for job, runtime, platform, rules in self._sched.get_schedule(event):
today at 12:11:55 File "/usr/local/lib/python3.11/site-packages/kernelci/scheduler.py", line 44, in get_schedule
today at 12:11:55 for config in self.get_configs(event, channel):
today at 12:11:55 File "/usr/local/lib/python3.11/site-packages/kernelci/scheduler.py", line 39, in get_configs
today at 12:11:55 if sched_event.items() <= event.items():
today at 12:11:55 ^^^^^^^^^^^
today at 12:11:55AttributeError: 'str' object has no attribute 'items'
today at 12:11:55
today at 12:11:55Traceback (most recent call last):
today at 12:11:55 File "/home/kernelci/./pipeline/scheduler.py", line 218, in
today at 12:11:55 status = opts.command(configs, opts)
today at 12:11:55 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
today at 12:11:55 File "/home/kernelci/./pipeline/scheduler.py", line 211, in __call__
today at 12:11:55 return Scheduler(configs, args).run()
today at 12:11:55 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
today at 12:11:55 File "/home/kernelci/pipeline/base.py", line 76, in run
today at 12:11:55 self._stop(context)
today at 12:11:55 File "/home/kernelci/./pipeline/scheduler.py", line 73, in _stop
today at 12:11:55 self._cleanup_paths()
today at 12:11:55 File "/home/kernelci/./pipeline/scheduler.py", line 58, in _cleanup_paths
today at 12:11:55 job_tmp_dirs = {
today at 12:11:55 ^
today at 12:11:55 File "/home/kernelci/./pipeline/scheduler.py", line 62, in
today at 12:11:55 if job.poll() is None
today at 12:11:55 ^^^^^^^^
today at 12:11:55AttributeError: 'Container' object has no attribute 'poll'
today at 12:13:49Container stopped
```

Start with pipeline/monitor.py and pipeline/scheduler.py, tracing how event.data reaches monitor processing and Scheduler.get_schedule(). Reproduce a node-channel event whose payload is a string, then inspect the scheduler paths for shell and Docker runtimes, including the cleanup failure in _cleanup_paths(). Done means these services handle the reported payload and runtime cases without the shown exceptions.

Written by the indexing model from the issue text.