feat(Surveys): Task to update rollout percentage for Adaptive Collection

[Phanatic]

Problem

Resolves : #25722

We currently allow %-based rollouts for surveys, as well as the option to set a response limit.

For some users with high volumes, that's not enough. Here is what we've heard:

Being able to specify a response limit per time period, e.g. "250 responses per month", or "7 responses per day"
Ideally, PostHog would adapt the rollout of surveys across the time period specified by the user, e.g. when a user wants 250 responses over a one-month period, we make sure they receive approximately 8 responses per day

Changes

Celery task for daily rollout updates

Created a Celery task to update the rollout percentage of a linked targeting_feature_flag based on the calculated response_sampling_daily_limits.

1. Ensures the feature flag's rollout_percentage aligns with the response_sampling_daily_limits for the current UTC date.
2. Updates the feature flag daily to maintain an even distribution of response collection.

Does this work well for both Cloud and self-hosted?

Yes

How did you test this code?

Celery task:

1. Confirms that the feature flag's rollout_percentage is updated correctly based on the response_sampling_daily_limits for today in UTC.
2. Ensures smooth operation for various sampling intervals and edge cases.

[sentry-io]

Suspect Issues

This pull request was deployed and Sentry observed the following issues:

• ‼️ CHQueryErrorNotAnAggregate: DB::Exception: Column properties is not under aggregate function and not in GROUP BY. Have colu... posthog.tasks.tasks.update_survey_adaptive_samp... View Issue

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