[risk=low][RW-13494] Renaming of free tier in many locations

[jmthibault79]

Similar to #8994, this is a cleanup PR renaming "expired" and "expiry" to "exhausted" in the context of initial credits where the user has spent above their limit. "Expired" should be restricted to when a user has passed the expiration time of their initial credits. Also rename "free tier" and "free credits" to "initial credits" where appropriate.

This PR is not intended to be comprehensive. Many references to Free Tier remain.

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[jmthibault79]

these can be useful more generally