This PR removes all leniency in the conversion of Strings to booleans: "true"
is converted to the boolean value `true`, "false" is converted to the boolean
value `false`. Everything else raises an error.
This change disables the _all meta field by default.
Now that we have the "all-fields" method of query execution, we can save both
indexing time and disk space by disabling it.
_all can no longer be configured for indices created after 6.0.
Relates to #20925 and #21341Resolves#19784
When using dynamic templates, ES will now throw an exception if a
`match_mapping_type` is used that doesn't correspond to an actual type.
Relates to #17285