Controlling the length of a broken beam

[Knute Snortum]

I have a Chopin piece where the notes form a broken beam across a key
change and break (see first attachment broken-beam-over-key-change.)
 LilyPond has drawn the stem and beam long in the upper right-hand corner
to avoid the key change.  I'm not sure I like that and I'm trying to change
it.  I can shorten the stem with the \alterBroken command but then the beam
collides with the key change (see second attachment
broken-beam-over-key-change-modified.)

Is there a way to shorten the upper right-hand broken beam?  Below is the
MWE:

%%%
\version "2.24.4"
\language "english"

\paper {
  indent = 0
  ragged-right = ##t
}

\relative {
  \time 6/8
  \key cs \minor
  c'8 r <bf a'>[( c]) r
    \alterBroken positions #'((2 . 2) (0 . 0)) Beam % comment this to see
default behavior
    <bf g'>[( |
  \bar "||"
  \key af \major
  \break
  c8])
}
%%%

--
Knute Snortum