Constant deltachat::quota::QUOTA_ALLCLEAR_PERCENTAGE

pub const QUOTA_ALLCLEAR_PERCENTAGE: u64 = 75;

if quota is below this value (again), QuotaExceeding is cleared.

This value should be a bit below QUOTA_WARN_THRESHOLD_PERCENTAGE to avoid jittering and lots of warnings when quota is exactly at the warning threshold.

We do not repeat warnings on a daily base or so as some provider providers report bad values and we would then spam the user.