## Is your feature request related to a problem?
See [this](https://github.com/PostHog/posthog/pull/9139/files/2754c0fd6633c806def5c328d491421ae7de0c19#diff-7f0217a57a02b6ebd709f6aa7bf43760b2d5a53069aee2b7fea27fdad1caadf1) for more info.


## Describe the solution you'd like

> This is used by django-rest-hooks, the library we use to integrate with Zapier. Specifically, this fires our Zapier integration's Triggers. However, the only trigger that actually matters is the "action_performed" one, and that has been completely delegated to the plugin server for a while. We can remove this Python cruft then, along with django-rest-hooks, but first we need to make sure action_defined and annotation_created actually are unused, and roll out an update to https://github.com/PostHog/posthog-zapier that'd remove those two completely.


## Describe alternatives you've considered

Do nothing
posthog/settings/web.py
"OPTIONS": {
            "context_processors": [
                "django.template.context_processors.debug",
                "django.template.context_processors.request",
                "django.contrib.auth.context_processors.auth",
                "django.contrib.messages.context_processors.messages",
            ]
        },
    }
]
WSGI_APPLICATION = "posthog.wsgi.application"
SOCIAL_AUTH_JSONFIELD_ENABLED = True
SOCIAL_AUTH_USER_MODEL = "posthog.User"
SOCIAL_AUTH_REDIRECT_IS_HTTPS = get_from_env("SOCIAL_AUTH_REDIRECT_IS_HTTPS", not DEBUG, type_cast=str_to_bool)
AUTHENTICATION_BACKENDS: List[str] = [
    "axes.backends.AxesBackend",
    "social_core.backends.github.GithubOAuth2",
    "social_core.backends.gitlab.GitLabOAuth2",
    "django.contrib.auth.backends.ModelBackend",
]
SOCIAL_AUTH_PIPELINE = (
    "social_core.pipeline.social_auth.social_details",
    "social_core.pipeline.social_auth.social_uid",
    "social_core.pipeline.social_auth.auth_allowed",
    "social_core.pipeline.social_auth.social_user",
    "social_core.pipeline.social_auth.associate_by_email",
    "posthog.api.signup.social_create_user",
    "social_core.pipeline.social_auth.associate_user",
    "social_core.pipeline.social_auth.load_extra_data",
    "social_core.pipeline.user.user_details",