fix: merge property descriptors when getter and setter come from different interfaces (#23939) (CP: 25.1)

[vaadin-bot]

This PR cherry-picks changes from the original PR #23939 to branch 25.1.

Original PR description

BeanUtil's dedup loop was replacing a read-only descriptor with a write-only one (or vice versa) instead of merging them. This caused BeanPropertySet to lose the getter when a parent interface provided it and a child interface provided the setter.

Fixes #20814

[vaadin-bot]

This PR is eligible for auto-merging policy, so it has been approved automatically. If there are pending conditions, auto merge (with 'squash' method) has been enabled for this PR [Message is sent from bot]

[sonarqubecloud]

Quality Gate passed

Issues
148 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

[vaadin-bot]

This PR is eligible for auto-merging policy, so it has been approved automatically. If there are pending conditions, auto merge (with 'squash' method) has been enabled for this PR[Message is sent from bot]

[github-actions]

Test Results

 1 385 files  ±0   1 385 suites  ±0   1h 25m 4s ⏱️ -59s
 9 901 tests +4   9 830 ✅ +4  71 💤 ±0  0 ❌ ±0 
10 374 runs  +4  10 294 ✅ +4  80 💤 ±0  0 ❌ ±0 

Results for commit 02b218e. ± Comparison against base commit cd1a5d2.