Column relationship warning should be raised during synthesizer initialization only

[R-Palazzo]

Environment Details

SDV: 1.9.0

Error Description

As a user, when I define a column relationship for which I don't have access to the material to use it properly, I see a warning. This warning should be raised only during the synthesizer initialization and not during the column relationship definition.

Steps to reproduce

The following snippet code:

from sdv.metadata import SingleTableMetadata
from sdv.single_table import GaussianCopulaSynthesizer

metadata = SingleTableMetadata().load_from_dict({
    'columns': {
        'country': {'sdtype': 'country_code'},
        'city': {'sdtype': 'city'},
    }
})
metadata.add_column_relationship('address', ['country', 'city'])

raise this warning:
UserWarning: The metadata contains a column relationship of type 'address'. which requires the address add-on.This relationship will be ignored. For higher quality data in this relationship, please inquire about the SDV Enterprise tier.
The same warning is also raised after by:

synthesizer = GaussianCopulaSynthesizer(metadata)

Expected behavior

The warning should be raised during the syntheiszer initialization only.