test(e2e): ask a leader again while it declines a forwarded write - #4924

A follower forwards a coordinator write to whichever coordinator it last saw
leading, and the leader serves it only while it is ready. Nothing holds it
ready between the follower reading that it leads and the forwarded write
arriving, so the write can be declined for a state that has already passed,
and no state the caller can read beforehand settles whether the next one
will be served. The refusal is how the caller learns.

Every query in this file asks for something the test has just arranged, which
rules out the reasons a leader declines for good and leaves only the ones
that pass, so they share one seam that asks again on a budget. Asking a
follower to remove the leader is the exception, being declined for good, and
is asked once. The leader's own reason does not cross the wire, so the text a
caller matches on cannot tell a leader that was not ready from one that
refused for good, and only the caller's own request separates them.