security-flags: remove now defunct un-suffixed rust-cross package reference
security-flags: remove now defunct un-suffixed rust-cross package reference

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