refactor: migrate ENABLE_TAXES_DISPLAY to posthog

[asadali145]

What are the relevant tickets?

Closes https://github.com/mitodl/hq/issues/6369

Description (What does it do?)

Migrates ENABLE_TAXES_DISPLAY feature flag to posthog.

How can this be tested?

• Setup post hog account and required settings by following the instructions in feat: add posthog integration #3207
• Create a feature flag in the post hog and disable it.
• You won't see taxes at checkout.
• Now enable the flag and check that you see taxes at checkout.
• You must enable ECOMMERCE_FORCE_PROFILE_COUNTRY and add TaxRate for your profile country in the admin.
• Note: If the tax rate is applicable but this flag is false, you will see the adjusted amount at checkout.

[pdpinch]

I don't think there's any reason to keep this feature flag. The feature has been deployed, and there's no reason why we would turn it off (at least not in RC and production deployments).

[asadali145]

@cachob I am going to remove the feature flag ENABLE_TAXES_DISPLAY as per Peter's suggestion.

[arslanashraf7]

I don't think there's any reason to keep this feature flag. The feature has been deployed, and there's no reason why we would turn it off (at least not in RC and production deployments).

@pdpinch could you take a look at the other subtasks in https://github.com/mitodl/hq/issues/5825 and let us know what other flags are not needed?

[pdpinch]

@pdpinch could you take a look at the other subtasks in https://github.com/mitodl/hq/issues/5825 and let us know what other flags are not needed?

See https://github.com/mitodl/hq/issues/5825#issuecomment-2436216514

If the flag is currently True in production, we should plan to remove it. I would only consider keeping these flags if they are significantly valuable for developers. Otherwise, they are just tech debt.

[arslanashraf7]

See https://github.com/mitodl/hq/issues/5825#issuecomment-2436216514

Wow. Sorry, I missed that.