Create StatNameHandlerNotSupportedRule to ease upgrade to Airflow 2.0

[turbaszek]

This issue is part of #8765

Rule

Create StatNameHandlerNotSupportedRule which corresponds to

Drop plugin support for stat_name_handler

entry in UPDATING.md. This rule should allow users to check if their current configuration needs any adjusting
before migration to Airflow 2.0.

How to guide

To implement a new rule, create a class that inherits from airflow.upgrade.rules.base_rule.BaseRule.
It will be auto-registered and used by airflow upgrade-check command. The custom rule class has to have title,
description properties and should implement check method which returns a list of error messages in case of
incompatibility.

For example:

airflow/airflow/upgrade/rules/conn_type_is_not_nullable.py

Lines 25 to 42 in ea36166

	class ConnTypeIsNotNullableRule(BaseRule):
	title = "Connection.conn_type is not nullable"
	description = """\
	The `conn_type` column in the `connection` table must contain content. Previously, this rule was \
	enforced by application logic, but was not enforced by the database schema.
	If you made any modifications to the table directly, make sure you don't have null in the conn_type column.\
	"""
	@provide_session
	def check(self, session=None):
	invalid_connections = session.query(Connection).filter(Connection.conn_type.is_(None))
	return (
	'Connection<id={}", conn_id={}> have empty conn_type field.'.format(conn.id, conn.conn_id)
	for conn in invalid_connections
	)

Remember to open the PR against v1-10-test branch.

[FHoffmannCode]

Hi, I would like to take this task can you assign me? @potiuk @mik-laj @turbaszek

[Dr-Denzy]

I will like take up this task.

[turbaszek]

There's already PR fort this #11223, I rebased it and will merge once tests pass.

[eladkal]

The PR is stale.
@Dr-Denzy would you like to take this one?

[Dr-Denzy]

The PR is stale.
@Dr-Denzy would you like to take this one?

I am currently neck-deep in some k8s issues but I will be happy to jump in on this once I have more wiggle room.

[eladkal]

Closing as there will be no more releases of upgrade check