chore: update bazel cleanup mechanisms
The bazel cache size increases much faster then I expected, due to multi branchs and CIs. I increased the cahce limit to 50GB to reduce cleanup frequency. (we have max 100GB volumes for Cache) On the other side, for a more efficient cleanup, only CAS files that are older than 2 days get removed. It can increase the performance after cleanup the cache.
Edited by Xiao Pan