[Benchmark] Disable sycl-bench/lin_reg_coeff benchmark (#20156)

`lin_reg_coeff` seems to be sporadically causing a GPU hang on the BMG
runner: The hang is so bad that we are forced to restart the machine
when the hang happens.

Undoubtedly there is probably a driver issue involved here
(compute-runtime 25.31.34666.3 is used), but to ensure the CI runs
continuously I am disabling the test.

Author: ianayl

devops/scripts/benchmarks/benches/syclbench.py

@@ -86,7 +86,7 @@ def benchmarks(self) -> list[Benchmark]:
             # Gesumv(self), # validation failure
             # Gramschmidt(self), # validation failure
             KMeans(self),
-            LinRegCoeff(self),
+            # LinRegCoeff(self), # FIXME: causes serious GPU hangs on 25.31.34666.3
             # LinRegError(self), # run time < 1ms
             # MatmulChain(self), # validation failure
             MolDyn(self),