[EDGEHOG-DEVICE-RUNTIME][RUST] Set OPENSSL_NO_VENDOR in environment
If set, always find OpenSSL in the system, even if the vendored feature is enabled. This allows us to compile edgehog-device-runtime also in Yocto where an unofficial triple is used.
Note: with this change, the patch applied to Poky's layer regarding the forcing on the usage of an official triple, can be removed.