The line to display BT-748-Lot was incorrectly removed while backporting
changes from SDK 1.12.0: the field was removed in 1.12.0, but it should
still be displayed in older versions.

(cherry picked from commit 399d4bc)

Requiring the organisation identifier (BT-501-Organization-Company) to
be unique causes problems in some countries, so remove this rule.

Remove the corresponding assert in fields.json and the schematron rule.

Remove constraints that forbid a Buyer or a Tenderer to be a service
provider.
Remove corresponding schematron rules.

(cherry picked from commit 8ac3c74)