Fix issue in configuring metricsEnabledDimensions

[lucienlu-aws]

Issue #, if available:
#692

Description of changes:
Multilang users of KCL would run into the below error when attempting to configure the metricsEnabledDimensions of the KCL through the multilang properties files

Java.lang.NoSuchMethodException: software.amazon.kinesis.metrics.MetricsConfig.metricsEnabledDimensions(java.util.HashSet)

This commit fixes the type of the field so that multilang users can configure this field like this to omit emitting WorkerIdentifier dimension metrics to CloudWatch

# By default, KCL will emit metrics for Operation, ShardId, and WorkerIdentifier dimensions
# Specify the specific dimensions to emit metrics for
metricsEnabledDimensions = Operation,ShardId

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