Add ability to create zstd compressor with compression level

[DracoLi]

Why this should be merged

Needed to change the default compression level of zstd. This is needed by blockdb to use the BestSpeed compression level.

How this works

This PR adds a NewZstdCompressorWithLevel function to enable zstd compression with a custom level.

How this was tested

Unit tests and blockdb tests in #4201

Need to be documented in RELEASES.md?

Don't think so

[Copilot]

Pull Request Overview

This PR adds the ability to create a zstd compressor with a custom compression level to support blockdb's requirement for non-default compression levels.

• Introduces NewZstdCompressorWithLevel function that accepts a compression level parameter
• Refactors existing NewZstdCompressor to use the new function with default compression level
• Updates the compressor to use zstd.CompressLevel instead of zstd.Compress

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
utils/compression/zstd_compressor.go	Adds new constructor with level parameter and updates compression logic
utils/compression/compressor_test.go	Adds test coverage for the new constructor function

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