[mlir][vector] Add e2e test for SVE for vector.expandload when SEV2p2 hardware/emulation is available

https://github.com/llvm/llvm-project/pull/210288 extended `vector.compressstore` + `vector.expandload` to support scalable vectors.
* For `vector.compressstore`, I was able to write an e2e test targeting SVE2 (see Arm's [compact](https://developer.arm.com/documentation/111108/2026-03/SVE-Instructions/COMPACT--Copy-Active-vector-elements-to-lower-numbered-elements-) instruction) as QEMU already supports SVE 2 (tested with QEMU 9).
* For `vector.expandload`, the corresponding SVE instruction ([expand](https://developer.arm.com/documentation/111108/2026-03/SVE-Instructions/EXPAND--Copy-lower-numbered-vector-elements-to-Active-elements-)) requires SVE 2p2, which currently is not supported by QEMU (tested with QEMU 11.0.2, see also https://linaro.atlassian.net/browse/QEMU-975).

This issue is to serve as a reference and so that we don't forget to add a test for `vector.expandload` in the future.