CDH/KMS: remove ehsm from defaut features

eHSM crate is no longer maintained and archived. Also, it requires
openssl to be built thus cannot be built with musl.

This patch removes it from default features of `kms` crate. If one wants
to build CDH with eHSM support, `KMS_PROVIDER=ehsm` can be used when
executing Makefile of CDH.

Signed-off-by: Xynnn007 <xynnn@linux.alibaba.com>

confidential-data-hub/kms/Cargo.toml

@@ -48,7 +48,7 @@ anyhow.workspace = true
 tonic-build.workspace = true
 
 [features]
-default = ["aliyun", "kbs", "ehsm"]
+default = ["aliyun", "kbs"]
 
 aliyun = ["chrono", "hex", "p12", "prost", "rand", "reqwest/rustls-tls", "sha2", "tonic", "url", "yasna"]
 kbs = ["kbs_protocol"]