### Description

The health API response can become a few MBs (2-3MB if 50K indices are affected).

In less extreme situations the response can be in the 10s/100s of KB. 

It might be worthwhile looking into chunking its response (this might provide clients with a better experience too)
server/src/internalClusterTest/java/org/elasticsearch/discovery/StableMasterDisruptionIT.java
private void assertGreenMasterStability(Client client) throws Exception {
        assertMasterStability(client, HealthStatus.GREEN, containsString("The cluster has a stable master node"));
    }
    private void assertMasterStability(Client client, HealthStatus expectedStatus, Matcher<String> expectedMatcher) throws Exception {
        assertBusy(() -> {
            GetHealthAction.Response healthResponse = client.execute(GetHealthAction.INSTANCE, new GetHealthAction.Request(true)).get();
            String debugInformation = xContentToString(healthResponse);
            assertThat(debugInformation, healthResponse.findIndicator("master_is_stable").status(), equalTo(expectedStatus));
            assertThat(debugInformation, healthResponse.findIndicator("master_is_stable").symptom(), expectedMatcher);
        });
    }
    private String xContentToString(ToXContentObject xContent) throws IOException {
        XContentBuilder builder = JsonXContent.contentBuilder();
        xContent.toXContent(builder, ToXContent.EMPTY_PARAMS);
        return BytesReference.bytes(builder).utf8ToString();
    }
    private void ensureNoMaster(String node) throws Exception {
        assertBusy(
            () -> assertNull(
                client(node).admin().cluster().state(new ClusterStateRequest().local(true)).get().getState().nodes().getMasterNode()
            )
        );
    }
    /**
     * Verify that nodes fault detection detects a disconnected node after master reelection
     */
    public void testFollowerCheckerDetectsDisconnectedNodeAfterMasterReelection() throws Exception {
        testFollowerCheckerAfterMasterReelection(NetworkDisruption.DISCONNECT, Settings.EMPTY);
        assertGreenMasterStability(internalCluster().client());
    }