Fix config schema with multivector

[robbespo00]

This PR fixes a small bug when exporting the config of the collections.

Multivector config was reported twice in the collection config even if multivector flag was not enabled.

How to reproduce it

Create a simple python collection as follows:

collection = client.collections.create(
    name="Article",
)
config = client.collections.export_config(
        "Article"
    ).to_dict()

Looking at the config values you will see multivector config twice even though multivector was not enabled.

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Infrastructure as Code	0   0   0   0	View in Orca
Passed	SAST	0   0   0   0	View in Orca
Passed	Secrets	0   0   0   0	View in Orca
Passed	Vulnerabilities	0   0   0   0	View in Orca

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.24%. Comparing base (7987de5) to head (21c3a4a).
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1573      +/-   ##
==========================================
+ Coverage   88.17%   88.24%   +0.07%     
==========================================
  Files         256      256              
  Lines       17677    17678       +1     
==========================================
+ Hits        15586    15600      +14     
+ Misses       2091     2078      -13     

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[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Infrastructure as Code	0   0   0   0	View in Orca
Passed	SAST	0   0   0   0	View in Orca
Passed	Secrets	0   0   0   0	View in Orca
Passed	Vulnerabilities	0   0   0   0	View in Orca