Allow customization of worker grace period and sleep interval in Docker image

[Dogacel]

flagsmith/api/scripts/run-docker.sh

Line 36 in 165f95b

RUN_BY_PROCESSOR=1 python manage.py runprocessor --sleepintervalms 500

We should be able to configure the the task processors similar to how we can configure the server as shown below,

flagsmith/api/scripts/run-docker.sh

Lines 21 to 24 in 165f95b

	--timeout ${GUNICORN_TIMEOUT:-30} \
	--workers ${GUNICORN_WORKERS:-3} \
	--threads ${GUNICORN_THREADS:-2} \
	--access-logfile $ACCESS_LOG_LOCATION \

The configurable parameters should be:

flagsmith/docs/docs/deployment/configuration/task-processor.md

Lines 54 to 58 in 165f95b

	| Argument | Description | Default |
	| ------------------- | ------------------------------------------------------------------------- | ------- |
	| `--sleepintervalms` | The amount of ms each worker should sleep between checking for a new task | 2000 |
	| `--numthreads` | The number of worker threads to run per task processor instance | 5 |
	| `--graceperiodms` | The amount of ms before a worker thread is considered 'stuck'. | 20000 |

[Dogacel]

I believe we can close this as #3355 is merged.