unify test traits for subgroup and integer_ops tests

Filing this issue in response to a review comment for the cl_khr_integer_dot_product integer_ops tests:

https://github.com/KhronosGroup/OpenCL-CTS/pull/1276#discussion_r668047518

In short, the subgroup tests define test traits for different types:

https://github.com/KhronosGroup/OpenCL-CTS/blob/v2021-08-16-00/test_conformance/subgroups/subhelpers.h

After PR #1276 is merged there will be somewhat similar test traits for the integer_ops tests.

Task is to investigate how much duplication exists and to unify the test traits where it makes sense.

Start with test_conformance/subgroups/subhelpers.h and the integer_ops test traits introduced around PR #1276. Read the linked review discussion, compare the trait definitions, and identify duplication before deciding what can be unified. Done means the overlapping traits are consolidated where appropriate without changing test coverage or behavior.

Written by the indexing model from the issue text.