detect_sentiment api has limits of input size of 5kb

[ppeiris]

Code has been updated to make sure the api does not failed

Issue #, if available:

When the audio transcribe results are more than 5000 bytes, the detect_sentiment API call fails due to its input limitations
https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/comprehend/client/detect_sentiment.html

Description of changes:
Check the input text size to make sure it's within the 5000 bytes limit, and if it exists, then truncate it to use the first 5000 bytes.

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[rstrahan]

Thank you @ppeiris ! Merging now, and sorry for the delay.