refactor(hsolver_test): replace unique_ptr heap alloc with stack vars in bpcg test

The alpha/beta scaling constants passed to ModuleBase::gemm_op inside
hpsi_func were heap-allocated via std::unique_ptr<T>(new T(...)) and
then re-exposed through .get(). GEMM only reads these values (const T*
alpha / const T* beta in gemm_op::operator()), so heap allocation is
unnecessary — the lambda performs a fresh new/delete pair on every call
for no semantic benefit.

Replace with stack-local const T one(1.0) / const T zero(0.0) and pass
&one / &zero directly. The result is fully C++11-compatible (indeed
C++98-compatible), shorter, and removes the only std::unique_ptr use in
the file, so <memory> is no longer needed even indirectly through this
translation unit's own code.

Verified by building the MODULE_HSOLVER_bpcg test target:
  make -j 30 MODULE_HSOLVER_bpcg
  -> [100%] Built target MODULE_HSOLVER_bpcg

Author: abacus_fixer

source/source_hsolver/test/diago_bpcg_test.cpp

@@ -136,20 +136,18 @@ class DiagoBPCGPrepare
         const std::vector<T> &h_mat = DIAGOTEST::hmatrix_local;
         auto hpsi_func = [h_mat, dim](T *psi_in, T *hpsi_out,
                                 const int ld_psi, const int nvec) {
-            std::unique_ptr<T> one(new T(1.0));
-            std::unique_ptr<T> zero(new T(0.0));
-            const T *one_ = one.get();
-            const T *zero_ = zero.get();
+            const T one(1.0);
+            const T zero(0.0);
 
             base_device::DEVICE_CPU *ctx = {};
             // hpsi_out(dim * nvec) = h_mat(dim * dim) * psi_in(dim * nvec)
             ModuleBase::gemm_op<T, base_device::DEVICE_CPU>()(
                 'N', 'N',
                 dim, nvec, dim,
-                one_,
+                &one,
                 h_mat.data(), dim,
                 psi_in, ld_psi,
-                zero_,
+                &zero,
                 hpsi_out, ld_psi);
         };
         const int ndim = psi_local.get_current_ngk();