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 followersChecker.getKnownFollowers().isEmpty() : followersChecker.getKnownFollowers();
                } else {
                    final ClusterState lastPublishedState;
                    if (activePublication) {
                        
                        lastPublishedState = currentPublication.get().publishedState();
                    } else {
                        
                        lastPublishedState = coordinationState.get().getLastAcceptedState();
                    }
                    final Set<DiscoveryNode> lastPublishedNodes = new HashSet<>();
                    lastPublishedState.nodes().forEach(lastPublishedNodes::add);
                    assert lastPublishedNodes.remove(getLocalNode()); 
                    assert lastPublishedNodes.equals(followersChecker.getKnownFollowers())
                        : lastPublishedNodes + " != " + followersChecker.getKnownFollowers();
                }
                assert becomingMaster
                    || activePublication
                    || coordinationState.get()
                        .getLastAcceptedConfiguration()
                        .equals(coordinationState.get().getLastCommittedConfiguration())
                    : coordinationState.get().getLastAcceptedConfiguration()
                        + " != "
                        + coordinationState.get().getLastCommittedConfiguration();
            } else if (mode == Mode.FOLLOWER) {
                assert coordinationState.get().electionWon() == false : getLocalNode() + " is FOLLOWER so electionWon() should be false";
                assert lastKnownLeader.isPresent() && (lastKnownLeader.get().equals(getLocalNode()) == false);
                assert joinAccumulator instanceof JoinHelper.FollowerJoinAccumulator;
                assert peerFinderLeader.equals(lastKnownLeader) : peerFinderLeader;
                assert electionScheduler == null : electionScheduler;