chore(*): removed unneeded imports (#18926)
This is another run of https://github.com/leanprover-community/mathlib/pull/17568, scrubbing unnecessary imports.
Like last time we only remove genuinely unneeded imports, and leave merely transitively redundant imports alone.
(I *still* disagree with the objectors to removing transitively redundant imports
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
Co-authored-by: Eric Wieser <wieser.eric@gmail.com>
