Remove old API key in stage when release is cut

[patphongs]

Summary

What we're after:
The private API key name has changed. We need to remove the old FEC_WEB_API_KEY from stage when release is cut now that we're using FEC_WEB_API_KEY_PRIVATE.

Completion criteria

• Update stage environment var for private key as noted above
• Make sure stage and prod aren't using the same keys, set up new ones if needed
• Delete the old private key variable FEC_WEB_API_KEY
• Test to make sure the parts of the site that access the API do not break (Such as calendar, data sections, candidate and committee profile pages, etc.)

[lbeaufort]

@patphongs here is the follow up task #3029 - the “private” keys are already in place in all three environments. If we waited to change the keys until deploy we would have a brief outage.

[patphongs]

Closing, this is a duplicate