refactor: correct loop syntax for synchronous iterations

[jbpionnier]

• Replace for-await-of with for-of in synchronous contexts
• Affects server cleanup, event processing, and test iterations
• No functional changes, just proper async/sync usage

Motivation and Context

This change fixes incorrect usage of for await...of loops in synchronous contexts throughout the codebase.

How Has This Been Tested?

• All existing tests continue to pass
• The functionality remains identical as these changes only correct syntax without altering behavior
• Verified that server cleanup, event processing, and test iterations work as expected

Breaking Changes

None. This is purely a syntax correction with no functional changes.

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

The changes affect the following areas:

• Server shutdown procedures in example servers
• Event processing in InMemoryEventStore
• Test iterations in middleware tests
• Resource template processing in McpServer