tera should support range delete and execute gc as fast as possible

思路：
1）例如现有区间是[1,...,100), 需要删除1~50的数据。采用类似split的方法，将manifest中文件区间改成[50,...,100)，tablet被重新load后，[1,...,50]的数据将被丢弃，后续master的gc发现这些sst没有引用，将被gc掉。

The issue proposes range deletion by changing the manifest range and reloading the tablet, followed by master GC of unreferenced SSTs. No files or tests are named; start by tracing the manifest, tablet reload, and master GC entry points. Done means the requested range is discarded and the resulting unreferenced SSTs are collected as described.

Written by the indexing model from the issue text.