TS1 fd file input every run with Unicode engines

[davidcarlisle]

Minimal example showing the current behaviour

\RequirePackage{latexbug}       % <--should be always the first line (see CONTRIBUTING)!
\documentclass{article}

\begin{document}
x
\end{document}

This inputs

/usr/local/texlive/2024/texmf-dist/tex/latex/base/ts1cmr.fd

at begin document as latex checks the default setup for TS1 encoding. 8 bit formats have already input this file but for Unicode engines ts1lmr.fd is preloaded but the cm one is then loaded at run time.

We could preload the fd file during format creation at the time other fd files are preloaded.