[AArch64][nfc] Remove duplicate [us]addl tests (#152664)
in the following list we keep the first test:
- extadd[us]_v8i8_i16, test_vaddl_[us]8, [us]addl8h
- extadd[us]_v4i16_i32, test_vaddl_[us]16, [us]addl4s
- extadd[us]_v2i32_i64, test_vaddl_[us]32, [us]addl2d
