As the title says. These tasks should be batched because they can arise from ILM actions.

Relates #77466
server/src/test/java/org/elasticsearch/cluster/metadata/MetadataIndexAliasesServiceTests.java
ClusterState after = service.applyAliasActions(
            before,
            singletonList(new AliasAction.Add(index, "test", null, null, null, null, null))
        );
        IndexAbstraction alias = after.metadata().getIndicesLookup().get("test");
        assertNotNull(alias);
        assertThat(alias.getType(), equalTo(IndexAbstraction.Type.ALIAS));
        assertThat(alias.getIndices(), contains(after.metadata().index(index).getIndex()));
        assertAliasesVersionIncreased(index, before, after);
        
        before = after;
        after = service.applyAliasActions(
            before,
            Arrays.asList(new AliasAction.Remove(index, "test", true), new AliasAction.Add(index, "test_2", null, null, null, null, null))
        );
        assertNull(after.metadata().getIndicesLookup().get("test"));
        alias = after.metadata().getIndicesLookup().get("test_2");
        assertNotNull(alias);
        assertThat(alias.getType(), equalTo(IndexAbstraction.Type.ALIAS));
        assertThat(alias.getIndices(), contains(after.metadata().index(index).getIndex()));
        assertAliasesVersionIncreased(index, before, after);
        
        before = after;
        after = service.applyAliasActions(before, singletonList(new AliasAction.Remove(index, "test_2", randomBoolean())));
        assertNull(after.metadata().getIndicesLookup().get("test"));
        assertNull(after.metadata().getIndicesLookup().get("test_2"));
        assertAliasesVersionIncreased(index, before, after);
        
        final ClusterState finalCS = after;