Fix smoke test substitution

[jakebailey]

I just merged the smoke test from #51464, but while it passed, I reread the logs on main and saw that it didn't actually work as expected; the heredoc wasn't in the right format and so was interpolating some of the code when I just wanted it raw.

Maybe I should just make it a script in the repo :\

[weswigham]

Does the ending sequence not need to change?

[jakebailey]

Nope, this is some silly bashism where if you quote the string (single or double), then it won't interpolate the string, but the ending sequence is still the same. Annoying. https://stackoverflow.com/questions/22697688/how-to-cat-eof-a-file-containing-code

I tested it locally this time...

[jakebailey]

Alright, there's now logging so one can see what it's doing, kinda like playwright. Which, begs the question as to whether or not I should be just making a smoke test script which tests all of that together instead, but that's another day.