Switch to `include_optimized` once Revise handles the 2-argument form of `include`

See https://github.com/trixi-framework/Trixi.jl/pull/643#issuecomment-867329976 and https://github.com/timholy/Revise.jl/issues/634. The necessary code is still included but commented out
```julia
# TODO: include_optimized
# This should be used everywhere (except to `include("interpolations.jl")`)
# once the upstream issue https://github.com/timholy/Revise.jl/issues/634
# is fixed; tracked in https://github.com/trixi-framework/Trixi.jl/issues/664.
# # By default, Julia/LLVM does not use fused multiply-add operations (FMAs).
# # Since these FMAs can increase the performance of many numerical algorithms,
# # we need to opt-in explicitly.
# # See https://ranocha.de/blog/Optimizing_EC_Trixi for further details.
# function include_optimized(filename)
# include(expr -> quote @muladd begin $expr end end, filename)
# end
```

Start with the commented `include_optimized` code in the issue and inspect where the corresponding `include` calls are used in the repository. Check the linked Revise.jl issue and Trixi.jl discussion first; this is done when Revise supports the two-argument form and the optimized include path can be enabled in the intended locations.

Written by the indexing model from the issue text.