fix: correctly use bytebuffer slice in decodecontexts method

[brittytino]

Description

This PR fixes the decodeContexts method in the FailoverListener class to properly use the ByteBuffer slice. Previously, the slice was created but not used, which could lead to incorrect reading of bytes and potential decoding errors.

The fix assigns the sliced buffer to a variable and reads from it, ensuring correct handling of the ByteBuffer without modifying the original buffer's position.

Changes

• Assigned byteBuffer.slice() to a local variable before reading data
• Used the slice for reading the JSON byte array

Why

This correction ensures the failover context decoding is reliable and respects ByteBuffer semantics, preventing subtle bugs in failover context processing.

No other functionality or features were changed.

[CLAassistant]

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