Remove unused target_vectors field from serialisation, update protos for new reserved values

[tsmith023]

weaviate/weaviate#9503

[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

❌ Patch coverage is 92.30769% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 86.96%. Comparing base (bdc6481) to head (e20c6fd).
⚠️ Report is 86 commits behind head on main.

Files with missing lines	Patch %	Lines
weaviate/collections/grpc/shared.py	92.30%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1854      +/-   ##
==========================================
+ Coverage   86.80%   86.96%   +0.15%     
==========================================
  Files         273      273              
  Lines       19059    19089      +30     
==========================================
+ Hits        16544    16600      +56     
+ Misses       2515     2489      -26     

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