Summary

Removes the pluginManagement.resolutionStrategy.eachPlugin block from clients/kotlin/settings.gradle.kts. Net −17 lines.

Why it's no longer needed

PR #176 added the block on a wrong hypothesis (that the ESRP build env's Maven mirror was missing the tiny <plugin-id>.gradle.plugin marker POMs). The real cause was 1ES Network Isolation silently blocking the public Maven Central / Gradle Plugin Portal entirely. That root cause is now fixed in the vscode-engineering maven-package template via a new customMavenRegistry parameter + Gradle init script that routes resolution through the Monaco Azure Artifacts Maven feed (which mirrors Maven Central upstream, including plugin marker POMs).

Validation

• GHA Kotlin CI ✅
• Manual ADO publish-pipeline dry-run (publish unticked) ✅

Follow-ups

• Close kotlin: route serialization plugin to its own maven artifact #177 (the fixup PR that patched a bug in the eachPlugin mapping — now irrelevant since the whole block is gone)
• Delete stale branches hotfix/kotlin-plugin-resolution, hotfix/kotlin-serialization-plugin, test/kotlin-pin-2.1.20, and this one
• Bump ref: connor4312/maven-pipeline in clients/kotlin/pipeline.yml to the stable ref once the vscode-engineering template change lands