codgen: make the Memory GEP an inbounds GEP (#55107)
The Julia memory model is always inbounds for GEP.
This makes the code in https://github.com/JuliaLang/julia/issues/55090
look almost the same as it did before the change. Locally I wasn't able
to reproduce the regression, but given it's vectorized code I suspect it
is backend sensitive.
Fixes https://github.com/JuliaLang/julia/issues/55090
Co-authored-by: Zentrik <Zentrik@users.noreply.github.com>
