feat: deactivate 'jemallocator' in signer

It is not needed anymore as we don't use anymore big HashMaps
to store the leaves of the Merkle trees used to sign the Cardano
transactions in the signer.

mithril-signer/Cargo.toml

@@ -54,7 +54,7 @@ prometheus-parse = "0.2.5"
 slog-term = "2.9.0"
 
 [features]
-default = ["jemallocator"]
+default = []
 
 bundle_openssl = ["dep:openssl", "dep:openssl-probe"]
 jemallocator = ["dep:tikv-jemallocator"]