Remove defunct @Shopify/infrastructure-tooling from CODEOWNERS

The @Shopify/infrastructure-tooling team no longer exists and should be
removed from CODEOWNERS files. This change removes the team reference
from this repository's CODEOWNERS file.

Changes:
- Line 1: Removed from default owners

@Shopify/application-infrastructure is already present as a codeowner
and will continue to receive review requests.

Generated with Claude Code (https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: aqeelvn

.github/CODEOWNERS

@@ -1 +1 @@
-* @Shopify/infrastructure-tooling @Shopify/application-infrastructure
+* @Shopify/application-infrastructure