Disable LevelDB snappy feature (#7235)

Disable the `snappy` feature of LevelDB to prevent compilation issues with CMake 4.0, e.g.

https://github.com/sigp/lighthouse/actions/runs/14182783816/job/39732457274?pr=7231

We do not use Snappy compression in LevelDB, and do not need to compile this. This might also shave a few seconds off compilation!

Author: michaelsproul

beacon_node/store/Cargo.toml

@@ -22,7 +22,7 @@ directory = { workspace = true }
 ethereum_ssz = { workspace = true }
 ethereum_ssz_derive = { workspace = true }
 itertools = { workspace = true }
-leveldb = { version = "0.8.6", optional = true }
+leveldb = { version = "0.8.6", optional = true, default-features = false }
 logging = { workspace = true }
 lru = { workspace = true }
 metrics = { workspace = true }