[SYCL][Graph] Fix missing includes for e2e tests using reduction (#15115)

Issue resulting of incomplete finer grained includes
#13846

Author: reble

sycl/test-e2e/Graph/Inputs/dotp_buffer_reduction.cpp

@@ -1,6 +1,7 @@
 // Tests creating a dotp operation which uses a sycl reduction with buffers.
 
 #include "../graph_common.hpp"
+#include <sycl/reduction.hpp>
 
 int main() {
   queue Queue{};

sycl/test-e2e/Graph/Inputs/dotp_usm_reduction.cpp

@@ -2,6 +2,7 @@
 // operation which uses a sycl reduction with USM memory.
 
 #include "../graph_common.hpp"
+#include <sycl/reduction.hpp>
 
 int main() {
   queue Queue{};

sycl/test-e2e/Graph/Inputs/sub_graph_reduction.cpp

@@ -2,6 +2,7 @@
 // reduction as well as a sub-graph.
 
 #include "../graph_common.hpp"
+#include <sycl/reduction.hpp>
 
 int main() {
   queue Queue{};