Autogenerated structures with unused lifetimes (manually removed)

[RoDmitry]

Lifetimes for input structures were added in #60, but some lifetimes are unused, and have been removed manually.
To automate that, it needs to check (in xtask/src/preprocess_openapi.rs mark_borrowed_data()) recursively that the inner types contain at least one field with a type of string.

Examples of autogenerated structures with extra lifetimes:

CollectionUpdateSchema
ImportDocumentsParameters
DeleteKeyParams
ToggleSlowRequestLogParams
ToggleSlowRequestLogRequest

Different issue but also related to #60: somehow NlSearchModelCreateSchema (in UpdateNlSearchModelParams) thinks that it isPrimitiveType, maybe some mistake in openapi.yml.