This is the result of running the generate_ecs_fieldmap script against
ECS' 8.0 branch.

This is a required field for e.g. scaled_float fields, so we need to
reflect its value in our field map.

It does not appear that this value was ever being set, nor does this
value appear in ECS' flat output, so I'm removing it for now to keep our
types as accurate as possible.

This is a required field for type: alias fields.

This now exceeds the default of 1000.

Apparently 1300 wasn't enough, either.

Makes this field optional, since the technical component template
doesn't currently use it.

Including the newest ECS fields, this index now exceeds 1600 fields.
This value should probably be derived from the composed template's
limits, but for now this allows the template to be created.