Set length of avro input file after memory input file is created

[mwong77]

Description

In AWS Athena, we currently support encrypting S3 objects using CSE-KMS. The size of these encrypted object will be greater than the size when unencrypted since padding will be added. The input.readAllBytes(); function strips the padding from an encrypted object so we have to update the length variable as well if we create a new in memory input file.

Additional context and related issues

Release notes

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## Section
* Fix some things. ({issue}`issuenumber`)

@nineinchnick @anusudarsan