Remove min_read_only_index_version from XContent node

We prefer to remove this information from the API since they
are not useful externally, impact the search shard API and
may be removed later (which would be a breaking change).

Follow-up elastic#118744

Author: tlrx

server/src/main/java/org/elasticsearch/cluster/node/DiscoveryNode.java

@@ -595,7 +595,6 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         builder.endArray();
         builder.field("version", versionInfo.buildVersion().toString());
         builder.field("min_index_version", versionInfo.minIndexVersion());
-        builder.field("min_read_only_index_version", versionInfo.minReadOnlyIndexVersion());
         builder.field("max_index_version", versionInfo.maxIndexVersion());
         builder.endObject();
         return builder;

server/src/test/java/org/elasticsearch/action/admin/cluster/reroute/ClusterRerouteResponseTests.java

@@ -127,7 +127,6 @@ public void testToXContentWithDeprecatedClusterState() {
                             ],
                             "version": "%s",
                             "min_index_version": %s,
-                            "min_read_only_index_version": %s,
                             "max_index_version": %s
                           }
                         },
@@ -219,7 +218,6 @@ public void testToXContentWithDeprecatedClusterState() {
                 clusterState.getNodes().get("node0").getEphemeralId(),
                 Version.CURRENT,
                 IndexVersions.MINIMUM_COMPATIBLE,
-                IndexVersions.MINIMUM_READONLY_COMPATIBLE,
                 IndexVersion.current(),
                 IndexVersion.current(),
                 IndexVersion.current()

server/src/test/java/org/elasticsearch/cluster/ClusterStateTests.java

@@ -213,7 +213,6 @@ public void testToXContent() throws IOException {
                               ],
                               "version": "%s",
                               "min_index_version":%s,
-                              "min_read_only_index_version":%s,
                               "max_index_version":%s
                             }
                           },
@@ -390,7 +389,6 @@ public void testToXContent() throws IOException {
                     ephemeralId,
                     Version.CURRENT,
                     IndexVersions.MINIMUM_COMPATIBLE,
-                    IndexVersions.MINIMUM_READONLY_COMPATIBLE,
                     IndexVersion.current(),
                     TransportVersion.current(),
                     IndexVersion.current(),
@@ -490,7 +488,6 @@ public void testToXContent_FlatSettingTrue_ReduceMappingFalse() throws IOExcepti
                           ],
                           "version" : "%s",
                           "min_index_version" : %s,
-                          "min_read_only_index_version" : %s,
                           "max_index_version" : %s
                         }
                       },
@@ -666,7 +663,6 @@ public void testToXContent_FlatSettingTrue_ReduceMappingFalse() throws IOExcepti
                 ephemeralId,
                 Version.CURRENT,
                 IndexVersions.MINIMUM_COMPATIBLE,
-                IndexVersions.MINIMUM_READONLY_COMPATIBLE,
                 IndexVersion.current(),
                 TransportVersion.current(),
                 IndexVersion.current(),
@@ -766,7 +762,6 @@ public void testToXContent_FlatSettingFalse_ReduceMappingTrue() throws IOExcepti
                           ],
                           "version" : "%s",
                           "min_index_version" : %s,
-                          "min_read_only_index_version" : %s,
                           "max_index_version" : %s
                         }
                       },
@@ -948,7 +943,6 @@ public void testToXContent_FlatSettingFalse_ReduceMappingTrue() throws IOExcepti
                 ephemeralId,
                 Version.CURRENT,
                 IndexVersions.MINIMUM_COMPATIBLE,
-                IndexVersions.MINIMUM_READONLY_COMPATIBLE,
                 IndexVersion.current(),
                 TransportVersion.current(),
                 IndexVersion.current(),

server/src/test/java/org/elasticsearch/cluster/node/DiscoveryNodeTests.java

@@ -223,15 +223,13 @@ public void testDiscoveryNodeToXContent() {
                             ],
                             "version" : "%s",
                             "min_index_version" : %s,
-                            "min_read_only_index_version" : %s,
                             "max_index_version" : %s
                           }
                         }""",
                     transportAddress,
                     withExternalId ? "test-external-id" : "test-name",
                     Version.CURRENT,
                     IndexVersions.MINIMUM_COMPATIBLE,
-                    IndexVersions.MINIMUM_READONLY_COMPATIBLE,
                     IndexVersion.current()
                 )
             )

x-pack/plugin/monitoring/src/test/java/org/elasticsearch/xpack/monitoring/collector/cluster/ClusterStatsMonitoringDocTests.java

@@ -462,7 +462,6 @@ public void testToXContent() throws IOException {
             pluginEsBuildVersion,
             Version.CURRENT,
             IndexVersions.MINIMUM_COMPATIBLE,
-            IndexVersions.MINIMUM_READONLY_COMPATIBLE,
             IndexVersion.current(),
             apmIndicesExist };
         final String expectedJson = """
@@ -818,7 +817,6 @@ public void testToXContent() throws IOException {
                     ],
                     "version": "%s",
                     "min_index_version":%s,
-                    "min_read_only_index_version":%s,
                     "max_index_version":%s
                   }
                 },