Fix #3347: "Run Code" reloads page in Matlab Problem

Instead of refreshing only the necessary parts,
"Run Code" reloads the whole page.

This commit fixes this behaviour, by refreshing the
specific elements belonging to the Problem instead.

Internal number:  LMS-2505

@antoviaque and @dianakhuang might be interested.
@adampalay Oh, sorry. We don't. Nice catch.

Should I remove it? (If I do, can I just update this pull request, or do we need to create another one.)