Once https://github.com/elastic/elasticsearch/issues/98503 is done, we can use our minimum version numbers in the SystemIndexMappingUpdate service instead of the old `Version` types. Mappings will be updated for a system index when all nodes have a matching descriptor mappings version for a system index, but this version is greater than what's stored in the mappings metadata.
server/src/test/java/org/elasticsearch/indices/SystemIndexMappingUpdateServiceTests.java
assertThat(
            SystemIndexMappingUpdateService.getUpgradeStatus(markShardsAvailable(createClusterState()), DESCRIPTOR),
            equalTo(UpgradeStatus.UP_TO_DATE)
        );
    }
    /**
     * Check that the manager will try to upgrade indices where their mappings are out-of-date.
     */
    public void testManagerProcessesIndicesWithOutdatedMappings() {
        assertThat(
            SystemIndexMappingUpdateService.getUpgradeStatus(
                markShardsAvailable(createClusterState(Strings.toString(getMappings("1.0.0")))),
                DESCRIPTOR
            ),
            equalTo(UpgradeStatus.NEEDS_MAPPINGS_UPDATE)
        );
    }
    /**
     * Check that the manager will try to upgrade indices where the mappings metadata is null or absent.
     */
    public void testManagerProcessesIndicesWithNullMetadata() {
        assertThat(
            SystemIndexMappingUpdateService.getUpgradeStatus(
                markShardsAvailable(createClusterState(Strings.toString(getMappings(builder -> {})))),
                DESCRIPTOR
            ),
            equalTo(UpgradeStatus.NEEDS_MAPPINGS_UPDATE)
        );
    }
    /**