Update the cache use in our workflows

[rdimitrov]

Motivation and Context

While debugging #631 noticed the cache was weirdly implemented, so the following PR updates the caching strategy across a few of our CI workflows.

• Replaced manual actions/cache with the built-in cache: true of setup-go
• Switched from manual golangci-lint installation to their official golangci-lint-action
• Removed redundant go mod download commands
• Added cache to the deployment pipeline for both staging and production (we should see faster Pulumi deployments)
• Same for the release workflow so hopefully faster release builds

How Has This Been Tested?

Breaking Changes

No

Types of changes

• 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 change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context