## Context
Regression on custom index creation where indexFieldMetadatas were not
saved properly in the DB. This is because we recently changed save() to
upsert() in the indexMetadataService and upsert does not handle nesting
insert properly.
I'm suggesting another fix where we separate indexMetadata creation and
index migration creation in 2 different functions. Since the goal was to
be able to recreate the index after being deleted when we changed the
tsvector expression and indexMetadata was actually not deleted, we
didn't need to recreate that part (hence the upsert) and only needed to
run a migration to create the actual index in the workspace schema.
I've updated the different services and now only call
createIndexMigration when we update a search vector expression.
Note: this is also fixing the sync-metadata command when running on a
workspace with a custom object (including the seeded workspace which has
the 'rocket' custom object), failing due to the missing 'searchVector'
indexFieldMetadata
By default, when custom fields are created, a searchVector field is
created based on the "name" field, which is also the label identifier by
default.
When this label identifier is updated, we want to update the
searchVector field to use this field as searchable field instead, if it
is of "searchable type" (today it is only possible to select a text or
number field as label identifier, while number fields are not
searchable).
