Move AsVector utility to fixture.h

PiperOrigin-RevId: 690577546
Change-Id: I2cebcffa1f2e3b0789f43e772e364c4762719ab3

test/benchmark/engine_util_sparse_benchmark_test.cc

@@ -19,7 +19,6 @@
 #include <vector>
 
 #include <benchmark/benchmark.h>
-#include <gtest/gtest.h>
 #include <absl/base/attributes.h>
 #include <mujoco/mjdata.h>
 #include <mujoco/mujoco.h>
@@ -37,11 +36,6 @@ using SqrMatTDFuncPtr = decltype(&mju_sqrMatTDSparse);
 // number of steps to roll out before benchmarking
 static const int kNumWarmupSteps = 500;
 
-// copy array into vector
-std::vector<mjtNum> AsVector(const mjtNum* array, int n) {
-  return std::vector<mjtNum>(array, array + n);
-}
-
 // ----------------------------- old functions --------------------------------
 
 void ABSL_ATTRIBUTE_NOINLINE mju_sqrMatTDSparse_baseline(