libarchive: Avoid zstd compression levels beyond 19 in zip format

We document Zstd compression levels up to 19.  However, the zip
format defines compression level range 0 through 9.  libarchive
scales it into range `ZSTD_minCLevel()` to `ZSTD_maxCLevel()`.
Zstd compression levels beyond 19 require large memory allocations
which may fail on some platforms, such as 32-bit Linux.

Fixes: #27712