If you're thinking it may be malicious, I think it's innocuous.
Try cat'ing /etc/skel/.bashrc
and see if the code in question in in there. My guess is it will be. When a new user's home directory is created, it copies all the files from /etc/skel
into the newly-created home directory. So, that directory is basically a "new user home directory template."
The code you posted (is missing an fi
at the end, but anyway) just looks like a utility for making it easier to organize your .bashrc into separate files rather than one big file. That's a common technique for various configuration files that a lot of distros commonly do. And I personally find that technique nice.
If you want to delete that code, it's not going to hurt anything to remove it (unless someday you add a ~/.bashrc.d/
directory and some file in there "doesn't work" and it confuses you why.)
Also, what distro are you on?