fix: add whitespace before seconds in trace-to-tree output (#67593)
### What?
Adds a whitespace character before seconds output of
`scripts/trace-to-tree.mjs`
### Why?
I was regexing a big output, looking for sources of slowness and failed
to do so because `\ss` would not find anything, whist `\sms` would,
because it printed whitespace before `ms` but not before `s`.
Co-authored-by: JJ Kasper <jj@jjsweb.site>