Fix sla checks being skipped when the later task instance is skipped

[doiken]

In the following code, even though t1 does not become "success",
no SLA miss occurs because the state of the subsequent t1 becomes "skipped".

from datetime import timedelta
from time import sleep

import pendulum
from airflow import DAG
from airflow.exceptions import AirflowSkipException, AirflowFailException
from airflow.operators.python import PythonOperator
from airflow.utils.dates import days_ago


def f():
    if pendulum.now().minute % 2 == 0:
        raise AirflowSkipException("skip")
    else:
        sleep(80)
        raise AirflowFailException("fail")

with DAG(
    dag_id="example_sla",
    schedule_interval="* * * * *",
    start_date=days_ago(2),
    catchup=False,
) as dag:
    PythonOperator(task_id="t1", python_callable=f, sla=timedelta(seconds=70))

In this PR, we would like to correct only the following behavior

• As-is
  • t1_1(state=other than success and skip): sla checks skipped by skipped t1_2
  • t1_2(state=skipped)
• To-be
  • t1_1(state=other than success and skip): sla checked
  • t1_2(state=skipped)

I believe the state=skipped behavior expected in the following PR is preserved.
#3370

[potiuk]

Remove or_ if you want to leave only one condition.

[potiuk]

I sm noy that familiar with the states here, But I am not sure if we want to do it, so I will defer to others, but we think about deprecating the whole SLA feature due to it's misbehaviours (see Draft AIP here https://cwiki.apache.org/confluence/display/AIRFLOW/%5BWIP%5D+AIP-57+SLA+as+a+DAG-Level+Feature) , so I am not sure if we want to invest into changing what we know is already pretty broken.

[doiken]

Thank you for letting me know about your plans.

I have corrected your point for now.
I believe the unit test failure in Tests / MSSQL2017 has nothing to do with my fix.

[potiuk]

I rebased it now to account for fix to mssql, but I think this one needs input from others

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 5 days if no further activity occurs. Thank you for your contributions.

[doiken]

There is a conflicting file, but I will leave it as is for stale.
If there is a demand for this PR, please let me know so I can fix it.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 5 days if no further activity occurs. Thank you for your contributions.