Correct release notes regarding rate limit

[rachel-feinberg]

Why are you making this change? (required)

There was a misreporting on the rate limit for the /users/export/ids endpoint. I removed all related entries because there actually wasn't a rate increase.

Rather, depending on when the user joined Braze, either 2,500 or 250 could apply to them:

• Onboarded before August 22, 2024: rate limit = 2,500
• Onboarded on or after August 22, 2024: rate limit = 250

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