Large keys are not stored in cache

### Which PikiwiDB functionalities are relevant/related to the feature request?

other

### Description

cache中不存入大key

### Proposed solution

cache中不存入大key
key维度string超过多少不存cache:16K
feild维度：cache-field-num-per-key 代码中已经实现，但是代码写的名字有问题

### Alternatives considered

zset-cache-field-num-per-key改为cache-field-num-per-key
