Possibility to remove metrics

I have a use case where I need to remove certain sub-metrics from a labeled metric. Ideally I could remove a bunch of them with a wildcard filter. The idea is to extend the .remove() method and allow for keyword arguments according to the defined label names as in the .labels(...) method. By not providing certain label names one could apply a wildcard operation.

Also would be happy to make a PR.

首先定位 Python 客户端中的 metric .remove() 实现以及 .labels(...) 的处理逻辑。定义关键字标签参数的行为，包括将省略的标签视为通配符，并考虑应如何验证删除多个匹配的子指标。