fix(folly): add libaio to system_libs for Linux

[jiaqizho]

Folly's AsyncIO uses libaio functions (io_submit, io_getevents, io_queue_init, io_queue_release), but libaio was not declared as a system library dependency in package_info(). This causes undefined reference errors at link time for consumers like milvus-storage.

Add "aio" to system_libs under the existing Linux-only condition for both the legacy recipe (folly/all) and the v2024 recipe (folly/v2024).

[jiaqizho]

@xiaofan-luan PTAL

[yhmo]

@jiaqizho
We will migrate the master branch of this repo to conan 2.x, please convert this pr to the "conan-1.x" branch: https://github.com/milvus-io/conanfiles/tree/conan-1.x
Now the "conan-1.x" branch is fully consistent with the master branch.
Once this pr is merged, the master branch will be used for conan2.x-only publish.
It is a part of this job: milvus-io/milvus#47425 (comment)