fix: fix slice init length

[cuishuang]

The intention here should be to initialize a slice with a capacity of len(staffCustomerIDs) rather than initializing the length of this slice.

The online demo: https://go.dev/play/p/q1BcVCmvidW

[cuishuang]

@coocood Hi, could you please review this PR? Thank you!

[coocood]

The intension is initializing the length, or the test would fail.

[Amr-Shams]

you are right here, but not right to the context of the ring buffer, when the ring buffer tries to set a segment a value, they store the length not the capacity of the object and the capacity of the object is not concerned with the implementation for several reasons, so TLDR: the capacity is ignored and the length is the actual matter attribute