[PM-35066] - remove legacy collections endpoint

[jaasen-livefront]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-35066

📔 Objective

Removes the legacy v1 PUT /api/ciphers/{id}/collections endpoint and its POST alias POST /api/ciphers/{id}/collections from CiphersController.

These endpoints were identified as still reachable during investigation of VULN-514. While the vulnerability itself was not deemed a security issue, the endpoints were flagged for removal. They are superseded by the v2 endpoint PUT /api/ciphers/{id}/collections_v2 (PutCollections_vNext), which remains intact.

[github-actions]

Checkmarx One – Scan Summary & Details – d87bd94c-d958-4b7c-8be0-3d53974d5718

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Fixed Issues (5)

Great job! The following issues were fixed in this Pull Request

Severity	Issue	Source File / Package
	CSRF	src/Identity/Controllers/AccountsController.cs: 138
	CSRF	src/Api/Vault/Controllers/CiphersController.cs: 763
	CSRF	src/Api/Vault/Controllers/CiphersController.cs: 763
	CSRF	src/Api/Vault/Controllers/CiphersController.cs: 763
	CSRF	src/Api/Vault/Controllers/CiphersController.cs: 763

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.14%. Comparing base (55d5f55) to head (4fb318c).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7520      +/-   ##
==========================================
+ Coverage   59.10%   59.14%   +0.04%     
==========================================
  Files        2078     2077       -1     
  Lines       91697    91832     +135     
  Branches     8150     8174      +24     
==========================================
+ Hits        54194    54315     +121     
- Misses      35572    35585      +13     
- Partials     1931     1932       +1     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud