fix: synchronize on pwa handler on map

[caalador]

Synchronize pwa handler on the requestHandlerMap instead of locking the session.

Locking and unlocking session may fire a push event that might make the server client sync faulty.

touches #14797

[github-actions[bot]]

Unit Test Results

   956 files  ±0     956 suites  ±0   52m 15s :stopwatch: +12s 6 085 tests ±0  6 031 :heavy_check_mark: +1  54 :zzz: ±0  0 :x:  - 1  6 347 runs   - 3  6 285 :heavy_check_mark:  - 2  62 :zzz: ±0  0 :x:  - 1 

Results for commit 359e770d. ± Comparison against base commit 475dde7b.

:recycle: This comment has been updated with latest results.

[sonarqubecloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

No Coverage information
0.0% Duplication

[vaadin-bot]

Hi @caalador and @caalador, when i performed cherry-pick to this commit to 9.0, i have encountered the following issue. Can you take a look and pick it manually? Error Message: Error: Command failed: git cherry-pick 997b395118986443b120baa114d494036e5b9659 error: could not apply 997b395118... fix: synchronize pwa handler on map (#14838) hint: After resolving the conflicts, mark them with hint: "git add/rm ", then run hint: "git cherry-pick --continue". hint: You can instead skip this commit with "git cherry-pick --skip". hint: To abort and get back to the state before "git cherry-pick", hint: run "git cherry-pick --abort".