Revert "Silence warning when requiring ruby-ts-mode"

This reverts commit bf817069.

We deliberately don't silence these warnings, so that a user who loads
the mode without having the grammar installed sees the warning and
realizes the problem in time to fix it.
1 job for master in 7 minutes and 48 seconds (queued for 2 minutes and 13 seconds)
Status Job ID Name Coverage
  Normal
failed #79093
test-lisp-inotify

00:07:48

 
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failed
test-lisp-inotify Normal
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Cleaning up project directory and file based variables
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