Clean up proliferation of std::chrono duration types

https://github.com/envoyproxy/envoy/pull/12225 ensured that arbitrary `std::chrono::{clock_type}::duration` constructors cannot be used as it introduces differences in time representation/units between different platforms. @lizan suggested also ensuring that `TimeSystem` (used in test infrastructure) should provide a concrete duration type to reduce the proliferation of `std::chrono` duration types. Concrete duration aliases were added in that class but all usages of `std::chrono` duration types are not yet converted to `TimeSystem::Nanosecond` etc.

This issue is a placeholder to denote that `std::chrono` duration types should be replaced with `TimeSystem` aliases and introduce a format check to prevent their re-addition in the future.