[SYCL] Fix unused plugin member after #15262 (#15312) #2333

Job	Run time
macOS / Build	10m 49s
build-win / Build + LIT	28m 42s
Linux (Self build + no-assertions) / Build + LIT	8m 48s
e2e-lin (Intel Arc A-Series Graphics with Level Zero, ["Linux", "arc"], --param matrix-xmx8=True ... / Intel Arc A-Series Graphics with Level Zero	11m 52s
e2e-lin (Intel GEN12 Graphics with Level Zero, ["Linux", "gen12"], --param gpu-intel-gen12=True, ... / Intel GEN12 Graphics with Level Zero	32m 13s
e2e-lin (Perf tests on Intel Arc A-Series Graphics system, ["Linux", "arc"], {"LIT_FILTER":"Perfo... / Perf tests on Intel Arc A-Series Graphics system	1m 30s
e2e-lin (AMD/HIP, ["Linux", "amdgpu"], ghcr.io/intel/llvm/ubuntu2204_build:latest-0300ac924620a51... / AMD/HIP	12m 29s
e2e-lin (Perf tests on Intel GEN12 Graphics system, ["Linux", "gen12"], {"LIT_FILTER":"Performanc... / Perf tests on Intel GEN12 Graphics system	1m 56s
e2e-win	0s
	1h 48m 19s

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