fix(ci): make lotus-devnet image(for devnet checks) slimmer

[hanabi1224]

Summary of changes

Changes introduced in this pull request:

• strip lotus binaries to reduce image size by ~200MB

➜  forest git:(main) ✗ docker image ls | grep lotus                                 
ghcr.io/chainsafe/lotus-devnet   2024-02-20-ab7dd00   b786800a387c   5 minutes ago    584MB
lotus-devnet                     latest               f7c9cbd43a9c   40 minutes ago   592MB
ghcr.io/chainsafe/lotus-devnet   2024-02-19-6f244ca   c76a8cfe78f3   7 hours ago      804MB

Reference issue to close (if applicable)

Closes

Other information and links

Change checklist

• [x] I have performed a self-review of my own code,
• [x] I have made corresponding changes to the documentation,
• [x] I have added tests that prove my fix is effective or that my feature works (if possible),
• [x] I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.