[BUG] Invalid time pattern placement in dynamic index pattern shuts down pipeline

Describe the bug
DataPrepper does not allow time patterns to be in dynamic index patterns unless they are the suffix of the pattern: https://github.com/opensearch-project/data-prepper/blob/main/data-prepper-plugins/opensearch/src/main/java/org/opensearch/dataprepper/plugins/sink/opensearch/index/AbstractIndexManager.java#L127

This causes the pipeline to shutdown at runtime when data is sent to a sink who's index pattern violates this condition.

ERROR org.opensearch.dataprepper.pipeline.common.PipelineThreadPoolExecutor - Pipeline [***] process worker encountered a fatal exception, cannot proceed further
java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: Time pattern can only be a suffix of an index

To Reproduce
Create a pipeline with this index pattern in an opensearch sink:

prefix-%{yyyy.MM.dd}-suffix

Expected behavior
It's unclear why DataPrepper does not support non-suffix time patterns. If this is not a hard restriction then I would expect this validation to be removed. If it is a hard restriction then I would expect this to be validated during initialization rather than throwing an exception and shutting down the pipeline at runtime.

Start with AbstractIndexManager.java at the validation around line 127 and trace how the OpenSearch sink handles the dynamic index pattern. Determine whether non-suffix time patterns should be supported or rejected during initialization; done means the chosen behavior no longer shuts down the pipeline at runtime for the reproduced pattern.