[SYCL] Remove OpenCL event interop test after feature removal (intel#1161)

intel/llvm#6570 removed the OpenCL interop get
member function from sycl::event.
SYCL/DeprecatedFeatures/event_creation_opencl.cpp used the removed
feature and should as such be removed.

Signed-off-by: Larsen, Steffen <[email protected]>

Author: steffenlarsen