refactor: improve user filtering logic for fetching unknown users

[MohamadJaara]

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PR Submission Checklist for internal contributors

• The PR Title

  • conforms to the style of semantic commits messages¹ supported in Wire's Github Workflow²
  • contains a reference JIRA issue number like SQPIT-764
  • answers the question: If merged, this PR will: ... ³

• The PR Description

  • is free of optional paragraphs and you have filled the relevant parts to the best of your ability

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What's new in this PR?

Issues

Fixed two O(n²) performance bottlenecks in UserRepository.kt:

• getAllRecipients() - slow when separating team members from other users
• fetchUsersIfUnknownByIds() - slow when filtering known vs unknown users

Solutions

Replaced List.contains() checks inside loops with Set-based lookups (O(1) instead of O(n)).

Needs releases with:

• GitHub link to other pull request

Testing

Test Coverage (Optional)

• I have added automated test to this contribution

How to Test

Briefly describe how this change was tested and if applicable the exact steps taken to verify that it works as expected.

Notes (Optional)

Specify here any other facts that you think are important for this issue.

Attachments (Optional)

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PR Post Submission Checklist for internal contributors (Optional)

• Wire's Github Workflow has automatically linked the PR to a JIRA issue

---

PR Post Merge Checklist for internal contributors

• If any soft of configuration variable was introduced by this PR, it has been added to the relevant documents and the CI jobs have been updated.

---

References

1. https://sparkbox.com/foundry/semantic_commit_messages
2. https://github.com/wireapp/.github#usage
3. E.g. feat(conversation-list): Sort conversations by most emojis in the title #SQPIT-764.

[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

[github-actions]

Test Results

0 tests   - 4 027   0 ✅  - 3 916   0s ⏱️ - 5m 26s
0 suites  -   680   0 💤  -   111 
0 files    -   680   0 ❌ ±    0 

Results for commit ca0dec8. ± Comparison against base commit 9a4dc9f.

♻️ This comment has been updated with latest results.

[github-actions]

Bencher Report

Branch	mo/refactor/improve-broadcast-message-recipent-list
Testbed	ubuntu-latest

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Benchmark	Latency	microseconds (µs)
com.wire.kalium.benchmarks.logic.CoreLogicBenchmark.createObjectInFiles	📈 view plot ⚠️ NO THRESHOLD	557.52 µs
com.wire.kalium.benchmarks.logic.CoreLogicBenchmark.createObjectInMemory	📈 view plot ⚠️ NO THRESHOLD	515,550.45 µs
com.wire.kalium.benchmarks.persistence.MessagesNoPragmaTuneBenchmark.messageInsertionBenchmark	📈 view plot ⚠️ NO THRESHOLD	1,390,944.36 µs
com.wire.kalium.benchmarks.persistence.MessagesNoPragmaTuneBenchmark.queryMessagesBenchmark	📈 view plot ⚠️ NO THRESHOLD	29,626.34 µs

🐰 View full continuous benchmarking report in Bencher

[codecov-commenter]

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 57.54%. Comparing base (6f6cbe6) to head (ca0dec8).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
.../com/wire/kalium/logic/data/user/UserRepository.kt	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3686      +/-   ##
===========================================
+ Coverage    57.49%   57.54%   +0.04%     
===========================================
  Files         1780     1780              
  Lines        59119    59135      +16     
  Branches      5757     5759       +2     
===========================================
+ Hits         33993    34027      +34     
+ Misses       22700    22678      -22     
- Partials      2426     2430       +4     

Files with missing lines	Coverage Δ
.../com/wire/kalium/logic/data/user/UserRepository.kt	70.16% <83.33%> (+6.93%)	⬆️

... and 2 files with indirect coverage changes

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