[Refactor] Remove objects which are only used for unit test

[acelyc111]

Proposed changes

We create some objects which are only used for unit tests, it's not necessary, and it may cause create duplicate instances for some classes.
This patch remove unnecessary instance of class BlockManager and StoragePageCache.

Types of changes

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• [] Bugfix (non-breaking change which fixes an issue)
• [] New feature (non-breaking change which adds functionality)
• [] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [] Documentation Update (if none of the other choices apply)
• Code refactor (Modify the code structure, format the code, etc...)

Checklist

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• [] I have create an issue on (Fix #ISSUE), and have described the bug/feature there in detail
• Compiling and unit tests pass locally with my changes
• [] I have added tests that prove my fix is effective or that my feature works
• [] If this change need a document change, I have updated the document
• [] Any dependent changes have been merged

Further comments

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[imay]

LGTM