fix: perform server navigation roundtrip only when client side navigation is completed

[mcollovati]

Description

In the case of server-side forward, even if the server callback is not required, the client-side navigation is completed when the React router blocker is still blocked, causing an unwanted roundtrip when location then changes to the desired state.
This change prevents server roundtrip if the blocker is in a blocked state.

Fixes #19822

Type of change

• Bugfix
• Feature

Checklist

• I have read the contribution guide: https://vaadin.com/docs/latest/guide/contributing/overview/
• I have added a description following the guideline.
• The issue is created in the corresponding repository and I have referenced it.
• I have added tests to ensure my change is effective and works as intended.
• New and existing tests are passing locally with my change.
• I have performed self-review and corrected misspellings.

Additional for Feature type of change

• Enhancement / new feature was discussed in a corresponding GitHub issue and Acceptance Criteria were created.

[sonarcloud]

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 SonarCloud

[github-actions]

Test Results

1 141 files  ± 0  1 141 suites  ±0   1h 11m 29s ⏱️ + 2m 24s
7 442 tests + 2  7 392 ✅ + 2  50 💤 ±0  0 ❌ ±0 
7 789 runs  +33  7 729 ✅ +33  60 💤 ±0  0 ❌ ±0 

Results for commit b87f741. ± Comparison against base commit 92c0853.