Remove a section which is setting missing libraries for build and test

[wshino]

Description

Related issue is here

This PR updates the setup documentation for the latest foundry-zksync

Before, when using foundry-zksync, it was necessary to deploy missing libraries in advance
Without this, neither unit tests nor integration tests could run

However, in the latest version, missing libraries are automatically detected and deployed
Because of this, both building and testing now work just like normal Foundry

Thus, I removed the section about setting missing libraries from the docs

However, setting missing libraries is still necessary for deployment

Type of change

• Bug fix (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)
• This change requires a documentation update

How Has This Been Tested?

• Test A
• Test B

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules