Revert "Give ,@ a prefix syntax in elisp-mode"

This reverts commit d003848b.

This leads to hangs in edebug-tests.
1 job for master in 73 minutes and 39 seconds (queued for 6 minutes and 11 seconds)
Status Job ID Name Coverage
  Normal
failed #47047
test-lisp-progmodes-inotify

01:13:39

 
Name Stage Failure
failed
test-lisp-progmodes-inotify Normal There has been a timeout failure or the job got stuck. Check your timeout limits or try again
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