feat: migrate from webflux to ktor

[jboix]

Description

Replaced the entire spring webflux/reactor pipeline with ktor based http clients.

Spring Boot remains only for dependency injection and configuration.

Changes Made

• Added a version catalog to the project ,see: https://docs.gradle.org/current/userguide/version_catalogs.html

Checklist

• I have followed the project's style and contribution guidelines.
• I have performed a self-review of my own changes.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.

[github-actions]

Coverage Report

Overall Project	89.04% -3.76%	🍏
Files changed	83.02%	🍏

File	Coverage
OpenSearchConfigurationProperties.kt	100%	🍏
HttpClientException.kt	100%	🍏
OpenSearchSetupConfiguration.kt	100%	🍏
ISMPolicySetupTask.kt	98.96%	🍏
IndexTemplateSetupTask.kt	98.96%	🍏
AliasSetupTask.kt	98.96%	🍏
IndexSetupTask.kt	98.95%	🍏
EventRepository.kt	97.25%	🍏
EventDispatcherClient.kt	94.58% -2.96%	🍏
HttpUtils.kt	94.48% -5.52%	🍏
OpenSearchSetupService.kt	91.67% -8.33%	🍏
RetryProperties.kt	53.44%	🍏
EventFlowProvider.kt	16.67% -83.33%	🍏
DataTransferApplicationRunner.kt	0% -5.1%	🍏

[github-actions]

🎉 This PR is included in version 6.2.0 🎉

The release is available on GitHub release

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