[BE] Use more GTest primitives in XPU unit tests (#119527)
# Motivation
Use `EXPECT_EQ` to refine XPU's UT when relying on gtest.
# Solution
use `EXPECT_EQ` directly instead of `ASSERT_EQ_XPU`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119527
Approved by: https://github.com/malfet
