Normal Hit Rate:
```
cache hit (direct) 1303
cache hit (preprocessed) 20
cache miss 219
cache hit rate 85.80 %
```
Previously, when we opened a worktree, the first compilation:
```
cache hit (direct) 0
cache hit (preprocessed) 0
cache miss 1404
cache hit rate 0.00 %
```
Now (using another different directory name, plus the current patch):
```
cache hit (direct) 4665
cache hit (preprocessed) 2517
cache miss 0
cache hit rate 100.00 %
```
see more in
https://ccache.dev/manual/4.7.4.html#_compiling_in_different_directories
docs: https://github.com/apache/doris-website/pull/3452