Runtime context shouldn't have start_date as a key

[amoghrajesh]

closes: #46754

#45294 added a new key "start_date" to the context, but context shouldnt have that. (https://github.com/apache/airflow/blob/v2-10-test/airflow/utils/context.py)

This was leading to the checks in determine_kwargs(self.python_callable, self.op_args, context) failing because the context keys were clashing with the example dag callable keys.

DAG used to test:

# This compares the datetime objects without timezones

# do something with time with both datetime and pendulum

# dags can do same thing

# give it a start date in the past

# proposed test plan:
# dag1:
#  - pendulum start time in the past
#  - standard datetime in the future as a user macro
#  - task that calculates the difference between the two and prints it
# dag2:
#  - standard start time in the past
#  - pendulum datetime in the future as a user macro
#  - task that calculates the difference between the two and prints it
# (future) outer dag:
# - run both and compare that they do the same things

# templated fields to calculate how long ago the start date is
from airflow.models.dag import DAG
from airflow.providers.standard.operators.python import PythonOperator

# from pendulum import datetime, timezone
import pendulum
import datetime
import pytz

etc_gmt13 = 'Etc/GMT-13'

chuuk = 'Pacific/Chuuk'

start_date = datetime.datetime(2021, 11, 25)


def subtractor(start_date, future_date):
    print(type(start_date), type(future_date))  # both strings, now find a way to compare
    if "T" in start_date or "T" in future_date:
        start_date = start_date.replace("T", "")
        future_date = future_date.replace("T", "")
    if "00:00:00" in start_date or "00:00:00" in future_date:
        start_date = start_date.replace("00:00:00", "")
        future_date = future_date.replace("00:00:00", "")

    if "+00:00" in start_date or "+00:00" in future_date:
        start_date = start_date.replace("+00:00", "")
        future_date = future_date.replace("+00:00", "")

    print(start_date, future_date)  # 2021-11-25 00:00:00+10:00 2135-11-25 00:00:00+13:00

    for i in start_date:
        if "-" == i:
            start_date = start_date.replace("-", "_")

    for i in future_date:
        if "-" == i:
            future_date = future_date.replace("-", "_")

    print(
        f"The newly filtered start date is {start_date} and the newly filtered future date is {future_date}")
    # 2021_11_25 +10:00, 2135_11_25 +13:00
    start_date_obj = datetime.datetime.strptime(start_date.strip(), "%Y_%m_%d")
    future_date_obj = datetime.datetime.strptime(future_date.strip(), "%Y_%m_%d")
    print(f"The start date object is: {start_date_obj}")
    print(f"The future date object is: {future_date_obj}")
    # now that the filtering has commenced
    # compare the 2 datetimes to ensure the result is the same across the 2 dags
    # the actual comparison

    the_difference = future_date_obj - start_date_obj
    print(f"This is the difference between the 2 dates in days: {the_difference}")
    print(f"This is the datatype of the difference betweeen the  2 datetime objects: {type(the_difference)}")


default_args = {
    "owner": "airflow",
}

with DAG(
    dag_id="compare_pendulum_datetime2",
    default_args=default_args,
    # datetime start date, pendulum future date as user defined macro
    start_date=start_date,
    schedule=None,
    catchup=False,
    user_defined_macros={
        "future_date": pendulum.datetime(2135, 11, 25)
    },
    tags=['core'],
) as dag:
    t1 = PythonOperator(
        task_id="subtract_future_and_start_date",
        python_callable=subtractor,
        op_args=[str(start_date), '{{ future_date }}']
    )

t1

{"timestamp":"2025-02-21T12:31:17.122121Z","level":"info","event":"The start date object is: 2021-11-25 00:00:00","chan":"stdout","logger":"task"}

{"timestamp":"2025-02-21T12:31:17.122194Z","level":"info","event":"The future date object is: 2135-11-25 00:00:00","chan":"stdout","logger":"task"}

{"timestamp":"2025-02-21T12:31:17.122272Z","level":"info","event":"This is the difference between the 2 dates in days: 41637 days, 0:00:00","chan":"stdout","logger":"task"}

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