Pass custom metric prefix if present to AbstractBuffer when using KafkaBuffer

[dinujoh]

Pass custom metric prefix if present to AbstractBuffer when using KafkaBuffer

Description

Pass custom metric prefix if present to AbstractBuffer when using KafkaBuffer. All the AbstractBuffer metrics should have customPrefix with KafkaBuffer. Also using consumer metrics for emptyCheckingConsumers.

Issues Resolved

Resolves #[Issue number to be closed when this PR is merged]

Check List

• New functionality includes testing.
• New functionality has a documentation issue. Please link to it in this PR.
  • New functionality has javadoc added
• Commits are signed with a real name per the DCO

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[oeyh]

Build is failing with this error:

/home/runner/work/data-prepper/data-prepper/data-prepper-plugins/kafka-plugins/src/test/java/org/opensearch/dataprepper/plugins/kafka/buffer/KafkaBufferTest.java:154: error: constructor KafkaBuffer in class KafkaBuffer cannot be applied to given types;
            return new KafkaBuffer(pluginSetting, bufferConfig, pluginFactory, acknowledgementSetManager, pluginMetrics, null, awsCredentialsSupplier, circuitBreaker);
                   ^
  required: PluginSetting,KafkaBufferConfig,PluginFactory,AcknowledgementSetManager,ByteDecoder,AwsCredentialsSupplier,CircuitBreaker
  found: PluginSetting,KafkaBufferConfig,PluginFactory,AcknowledgementSetManager,PluginMetrics,<null>,AwsCredentialsSupplier,CircuitBreaker
  reason: actual and formal argument lists differ in length