KIP-1006 — Remove SecurityManager Support

Discussion BrokerSecurity

Removes Kafka's compile-time and runtime dependencies on the Java `SecurityManager` API (including `AccessController`) from clients, core, and connect-runtime modules. JEP-411 deprecated `SecurityManager` in Java 17 and Java 23 already throws `UnsupportedOperationException` for legacy APIs when no `SecurityManager` is configured, making these calls a forward-compatibility hazard.

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