### Description

Dynamic mappings can greatly help the getting started experience but they currently don't apply to all types, one example is `dense_vector`.

It's been suggested to automatically map float arrays as dense vectors when there are more than 100 values, or a heuristic along these lines.
server/src/internalClusterTest/java/org/elasticsearch/index/mapper/DynamicMappingIT.java
mappings.endObject();
                }
            }
            mappings.endArray();
        }
        mappings.endObject();
        BulkRequest bulkRequest = new BulkRequest().setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE);
        bulkRequest.add(
            new IndexRequest("test").id("1")
                .source(XContentFactory.jsonBuilder().startObject().field("my_location", "41.12,-71.34").endObject())
                .setDynamicTemplates(Map.of("my_location", "foo_bar")),
            new IndexRequest("test").id("2")
                .source(XContentFactory.jsonBuilder().startObject().field("address.location", "41.12,-71.34").endObject())
                .setDynamicTemplates(Map.of("address.location", "bar_foo"))
        );
        final BulkResponse bulkItemResponses = client().bulk(bulkRequest).actionGet();
        assertTrue(bulkItemResponses.hasFailures());
        assertThat(bulkItemResponses.getItems()[0].getFailure().getCause(), instanceOf(DocumentParsingException.class));
        assertThat(
            bulkItemResponses.getItems()[0].getFailureMessage(),
            containsString("Can't find dynamic template for dynamic template name [foo_bar] of field [my_location]")
        );
        assertThat(bulkItemResponses.getItems()[1].getFailure().getCause(), instanceOf(DocumentParsingException.class));
        assertThat(
            bulkItemResponses.getItems()[1].getFailureMessage(),
            containsString("[1:21] Can't find dynamic template for dynamic template name [bar_foo] of field [address.location]")
        );
    }
    public void testDynamicRuntimeNoConflicts() {
        assertAcked(indicesAdmin().prepareCreate("test").setMapping("""