Differentiate machine learning job types

[lcawl]

In 7.1, we need to be able to differentiate between "anomaly detector jobs" and "data frame analytics jobs" in the documentation.

NOTE: Page names should remain unchanged to ease switching between versions. (For example, after 7.1 is released we don't want someone who selects "show current version" from the 7.0 "Put Job" page to be told the page doesn't exist.)

• Create attributes in https://github.com/elastic/docs/blob/master/shared/attributes.asciidoc that we can use in case the exact job types change: Adds shared attributes for ML jobs docs#688
• Update the existing content in the Stack Overview: https://www.elastic.co/guide/en/elastic-stack-overview/master/xpack-ml.html, https://www.elastic.co/guide/en/elastic-stack-overview/master/ml-troubleshooting.html, https://www.elastic.co/guide/en/elastic-stack-overview/master/ml-limitations.html. See [DOCS] Updates anomaly detection terminology in Stack Overview elasticsearch#44888, Updates anomaly detection job terminology in Stack Overview #444
• Update the existing content in the Elasticsearch Reference: https://www.elastic.co/guide/en/elasticsearch/reference/master/ml-settings.html, https://www.elastic.co/guide/en/elasticsearch/reference/master/ml-apis.html, https://www.elastic.co/guide/en/elasticsearch/reference/master/api-definitions.html
  See [DOCS] Updates terms in anomaly detection job APIs elasticsearch#44839, [DOCS] Updates terms in machine learning calendar APIs elasticsearch#44866, [DOCS] Updates terms in machine learning datafeed APIs elasticsearch#44883, [DOCS] Updates terms in machine learning get APIs elasticsearch#44986, ...
• Update the existing content in the Kibana Guide: https://www.elastic.co/guide/en/kibana/master/xpack-ml.html
  See [DOCS] Updates ML/anomaly detection terms in the Kibana guide kibana#41965
• Update the existing terminology in the Glossary: https://www.elastic.co/guide/en/elastic-stack-glossary/current/index.html See Adds job definitions to the Glossary #238
• Update the existing content in the Java REST client reference:
  https://www.elastic.co/guide/en/elasticsearch/client/java-rest/master/_machine_learning_apis.html: See [DOCS] Updates terms in anomaly detection job APIs elasticsearch#44839, [DOCS] Updates terms in machine learning calendar APIs elasticsearch#44866, [DOCS] Updates terms in machine learning datafeed APIs elasticsearch#44883, [DOCS] Updates terms in machine learning get APIs elasticsearch#44986 ...