on_config_changed lock fix: recursive lock in configservice

[kp-cat]

Describe the purpose of your pull request

• on_config_changed lock fix: Use recursive lock in ConfigService

Related issues (only if applicable)

• https://trello.com/c/RMYp6h55/452-python-sdk-ban-a-hooks-kiaj%C3%A1nl%C3%A1sa-a-configcatclientben-%C3%A9s-a-hookokn%C3%A1l-egy-configcatclient-is-menjen-param%C3%A9terben-invokeonconfigc

Requirement checklist (only if applicable)

• I have covered the applied changes with automated tests.
• I have executed the full automated test set against my changes.
• I have validated my changes against all supported platform versions.
• I have read and accepted the contribution agreement.

[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