### Body

The CLI:

`airflow variables set [-h] [-j] [-v] key VALUE`

https://airflow.apache.org/docs/apache-airflow/stable/cli-and-env-variables-ref.html#set_repeat1

Doesn't support adding description though column exists and we support it from Rest API:
https://airflow.apache.org/docs/apache-airflow/stable/stable-rest-api-ref.html#operation/post_variables

**The Task:**

Allow to set description from cli command

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
ARG_CFG_PATH,
            ARG_LOCAL,
            ARG_RAW,
            ARG_IGNORE_ALL_DEPENDENCIES,
            ARG_IGNORE_DEPENDENCIES,
            ARG_IGNORE_DEPENDS_ON_PAST,
            ARG_DEPENDS_ON_PAST,
            ARG_SHIP_DAG,
            ARG_PICKLE,
            ARG_JOB_ID,
            ARG_INTERACTIVE,
            ARG_SHUT_DOWN_LOGGING,
            ARG_MAP_INDEX,
            ARG_VERBOSE,
            ARG_READ_FROM_DB,
        ),
    ),
    ActionCommand(
        name="test",
        help="Test a task instance",
        description=(
            "Test a task instance. This will run a task without checking for dependencies or recording "
            "its state in the database"
        ),
        func=lazy_load_command("airflow.cli.commands.task_command.task_test"),
        args=(
            ARG_DAG_ID,
            ARG_TASK_ID,
            ARG_EXECUTION_DATE_OR_RUN_ID_OPTIONAL,
            ARG_SUBDIR,