rust: remove USE_LOCAL_RUST in favor of PACKAGECONFIG
rust: remove USE_LOCAL_RUST in favor of PACKAGECONFIG

jmesmon/meta-rust,meta-rust/meta-rust,jmesmon/meta-rust,meta-rust/meta-rust,cardoe/meta-rust,starlab-io/meta-rust,jmesmon/meta-rust,cardoe/meta-rust,meta-rust/meta-rust,meta-rust/meta-rust,cardoe/meta-rust,jmesmon/meta-rust,starlab-io/meta-rust,meta-rust/meta-rust,cardoe/meta-rust