[group_functions] Reduce test size to avoid overflow

[Nuullll]

This avoids meaningless overflowed results for reducing over smaller types (e.g. char).

Signed-off-by: Yilong Guo yilong.guo@intel.com
Co-authored-by: Jie Zhang jiez.zhang@intel.com

[vladimirkhashev]

Maybe it make sense to limit the size of the workgroup for reduce tests, because in the case when the size of the workgroup is large enough and the operation type is sycl::multiplies<T>, the test results will also be incorrect due to overflow. Also maybe init value (currently equals to 1442) for reduce operations can be changed that it can be represented by char type?

[keryell]

Thanks.
You need to fix the merge conflicts.

[Nuullll]

Thanks. I'll update per @vladimirkhashev 's suggestion.

[Nuullll]

Adding co-author: @jiezzhang