CAMEL-23430: Fix flaky tests in camel-kafka

[gnodet]

CAMEL-23430

Fix two flaky tests in camel-kafka:

KafkaConsumerAutoInstResumeRouteStrategyIT.testOffsetIsBeingChecked:

• Producer was never flushed or closed after sending messages — messages may not have been delivered to Kafka when the test starts consuming
• mock.assertIsSatisfied() was called without any wait timeout — the assertion checked immediately before the route had time to consume and process messages
• Fix: use try-with-resources for the producer with an explicit flush, and use Awaitility to wait for the mock assertion

KafkaIdempotentRepositoryEagerIT.createRepositoryTopic (via KafkaTestUtil.createTopic):

• The describeTopics() future had only a 5-second timeout, which is too tight when the Kafka broker is still warming up
• The AdminClient was never closed, leaking resources
• Fix: increase timeout to 30 seconds and use try-with-resources for the AdminClient

[github-actions]

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[github-actions]

🧪 CI tested the following changed modules:

• components/camel-kafka

⚠️ Some tests are disabled on GitHub Actions (@DisabledIfSystemProperty(named = "ci.env.name")) and require manual verification:

• components/camel-kafka: 3 test(s) disabled on GitHub Actions

All tested modules (8 modules)

• Camel :: JBang :: MCP
• Camel :: JBang :: Plugin :: Route Parser
• Camel :: JBang :: Plugin :: TUI
• Camel :: JBang :: Plugin :: Validate
• Camel :: Kafka
• Camel :: Launcher :: Container
• Camel :: YAML DSL :: Validator
• Camel :: YAML DSL :: Validator Maven Plugin

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