https://github.com/elastic/elasticsearch/pull/97304 removes several places that might do an expensive rebuild of the cluster state via `getStateForMasterService`. There's one other call we should be able to remove, in `JoinValidationService`, but it's a little tricky since we rely on seeing the last-accepted state for the cluster UUID validation, and it's not obviously ok to expose the last-accepted state without the no-master block.

This is a fairly minor issue because we do not do this join validation during elections, only if we're the elected master, and in that case `getStateForMasterService` is cheap. But that's not guaranteed, and we should strengthen this to avoid the that expensive step whenever possible.
server/src/main/java/org/elasticsearch/cluster/coordination/Coordinator.java
assert prevotingRound == null : prevotingRound;
                assert lastAcceptedClusterState.nodes().getMasterNodeId() == null : lastAcceptedClusterState;
                assert leaderChecker.currentNodeIsMaster() == false;
                assert lastKnownLeader.equals(Optional.of(leaderChecker.leader()));
                assert followersChecker.getKnownFollowers().isEmpty();
                assert lastKnownLeader.get().equals(applierState.nodes().getMasterNode())
                    || (applierState.nodes().getMasterNodeId() == null
                        && (applierState.term() < getCurrentTerm() || applierState.version() < getLastAcceptedState().version()));
                assert currentPublication.map(Publication::isCommitted).orElse(true);
                assert preVoteCollector.getLeader().equals(lastKnownLeader.get()) : preVoteCollector;
                assert clusterFormationFailureHelper.isRunning() == false;
            } else {
                assert mode == Mode.CANDIDATE;
                assert joinAccumulator instanceof JoinHelper.CandidateJoinAccumulator;
                assert peerFinderLeader.isPresent() == false : peerFinderLeader;
                assert prevotingRound == null || electionScheduler != null;
                assert lastAcceptedClusterState.nodes().getMasterNodeId() == null : lastAcceptedClusterState;
                assert leaderChecker.currentNodeIsMaster() == false;
                assert leaderChecker.leader() == null : leaderChecker.leader();
                assert followersChecker.getKnownFollowers().isEmpty();
                assert applierState.nodes().getMasterNodeId() == null;
                assert currentPublication.map(Publication::isCommitted).orElse(true);
                assert preVoteCollector.getLeader() == null : preVoteCollector;
                assert clusterFormationFailureHelper.isRunning();
            }
        }
    }
    public boolean isInitialConfigurationSet() {
        return getLastAcceptedState().getLastAcceptedConfiguration().isEmpty() == false;
    }