Remove all handling of index.mapper.dynamic

[peternied]

Description

index.mapper.dynamic's deprecation predates OpenSearch. We should remove any traces of this legacy setting from the system except to warn that the setting won't be actioned on.

The INDEX_MAPPER_DYNAMIC_SETTING should be ignored, it won't be, org.opensearch.action.support.AutoCreateIndex:

    public AutoCreateIndex(
        Settings settings,
        ClusterSettings clusterSettings,
        IndexNameExpressionResolver resolver,
        SystemIndices systemIndices
    ) {
        this.resolver = resolver;
        dynamicMappingDisabled = !MapperService.INDEX_MAPPER_DYNAMIC_SETTING.get(settings);
        this.systemIndices = systemIndices;
        this.autoCreate = AUTO_CREATE_INDEX_SETTING.get(settings);
        clusterSettings.addSettingsUpdateConsumer(AUTO_CREATE_INDEX_SETTING, this::setAutoCreate);
    }

• Originally posted by @reta in Warn about index.mapper.dynamic usage instead of erroring #11193 (comment)

Expected Result

Remove this legacy settings usage expect for purposes of warning about its removal and non-functionality.

[peternied]

[Triage - attendees 1 2 3 4 5]
Thanks for creating this issue

[andrross]

@peternied We need to fix this ASAP now that #11193 allows for indices to be created with this deprecated setting present, right?

[reta]

@peternied We need to fix this ASAP now that #11193 allows for indices to be created with this deprecated setting present, right?

So we need to check the indexVersionCreated and if the version is on or after V_2_0_0, we should reject index creation, the same we have to do for 2.x backport but lower the version to ~1.1.0 since we do not expect any indices created by OpenSearch to have this setting).

[peternied]

We need to fix this ASAP

This change was merged into 2.x, so it needs to target 2.13. I'll work on this soon and want to be clear no 2.12.1 change is needed.