build(deps): bump to core v1.0.0-alpha.1 and remove replaces

[julienrbrt]

Description

Follow-up of #21564.
Prerequisite of #21550

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Summary by CodeRabbit

• New Features
  • Updated the cosmossdk.io/core dependency to version v1.0.0-alpha.1, introducing potential new features and changes.
• Bug Fixes
  • Removed local path replacements for cosmossdk.io/core, aligning with the official module version to improve stability and compatibility.
• Chores
  • Restructured dependency management across multiple modules for better organization and clarity.