Abseil does not support C++11 anymore: https://github.com/google/oss-policies-info/blob/b842c39db88e6569dfe2cf98be434b03507cb503/foundational-cxx-support-matrix.md

NOTE: This is a breaking change because `std::integer_sequence<T>` requires `std::is_integral_v<T>`, but `absl::integer_sequence<T>` does not.

Unit tests will be deleted in a follow-up.

PiperOrigin-RevId: 589908215
Change-Id: I57a81e4451840304d5fba60bef286e81e024af9c