[mlir][SVE] Fix memory leaks in integration tests (#86488)

Buffers are no longer deallocated by One-Shot Bufferize - this is now
done by a separate buffer deallocation pass.

In order to see the leaks in SVE integration tests, use the following
CMake flags (enables the address sanitizer and SVE integration tests):

    -DLLVM_USE_SANITIZER="Address"
    -DMLIR_INCLUDE_INTEGRATION_TESTS=On
    -DMLIR_RUN_ARM_SVE_TESTS=On

Follow-up for #85366