Use zstd without dynamic linking due to musl usage (#19627)

Due to leaning towards `musl` builds, unit features for `zstd` and link
it statically too for Zed.


bfe1e34f59/zstd-safe/zstd-sys/build.rs (L260)
shows that `ZSTD_SYS_USE_PKG_CONFIG` env var can be used to return this
behavior.

Release Notes:

- N/A

crates/zed/Cargo.toml

@@ -125,8 +125,6 @@ winresource = "0.1"
 
 [target.'cfg(target_os = "linux")'.dependencies]
 ashpd.workspace = true
-# We don't use zstd in the zed crate, but we want to add this feature when compiling a desktop build of Zed
-zstd = { workspace = true, features = [ "pkg-config" ] }
 
 [dev-dependencies]
 call = { workspace = true, features = ["test-support"] }