replSetReconfig should be allowed to fail with InterruptedDueToReplStateChange when racing with an election

reconfig_during_election.js expects that a replSetReconfig command can always succeed when run during an election.

However, if the candidate was issued a replSetStepUp command, it is possible that the reconfig command can be killed by the RstlKillOpThread. In this case, we would fail with an InterruptedDueToReplStateChange error.

It is fine to fail with this error since this test is making sure that we do not invariant when a reconfig is running during an election. See SERVER-37255 for an in depth description of the bug.