fix(azure): correct EventHubs emulator test client builder usage

[kiview]

Problem

EventHubsEmulatorContainerTest.testWithEventHubsClient() was failing with:

AmqpException: The messaging entity 'sb://emulatorns1.eventhubs.emulator.net/eh1' could not be found.

The test called both .connectionString(emulator.getConnectionString()) and .fullyQualifiedNamespace("emulatorNs1") on EventHubClientBuilder. In the Azure SDK these two methods are mutually exclusive — .fullyQualifiedNamespace() overrides the endpoint from the connection string, causing the SDK to resolve emulatorNs1.eventhubs.emulator.net instead of the mapped localhost port.

Fix

Replace the broken chained calls with the two-arg connectionString(connectionString, eventHubName) overload, which correctly sets both the endpoint and entity name:

// Before (broken)
new EventHubClientBuilder()
    .connectionString(emulator.getConnectionString())
    .fullyQualifiedNamespace("emulatorNs1")  // overrides localhost endpoint!
    .eventHubName("eh1")
    .buildProducerClient();

// After (fixed)
new EventHubClientBuilder()
    .connectionString(emulator.getConnectionString(), "eh1")
    .buildProducerClient();

The emulator container implementation and config file (eventhubs_config.json) are correct and unchanged.