Force remote metadata checks on Muzzle retries

[aalbertjay]

Summary

• run Muzzle retries with Aether's always update policy
• give every retry fresh Aether SessionData so an earlier failed update check is not replayed
• preserve the original repository session configuration and local repository
• add an integration-style regression test that publishes metadata after the first cached miss and verifies the second attempt fetches it

Why

Aether records failed metadata transfers in the local repository and also memoizes update checks in the session. As a result, Muzzle's existing immediate and backoff retries return the first cached failure without issuing another remote request. A fresh copied session with a fresh SessionData and UPDATE_POLICY_ALWAYS makes each retry real.

Testing

• ./gradlew -p buildSrc :test -PrunBuildSrcTests --tests datadog.gradle.plugin.muzzle.MuzzleMavenRepoUtilsTest -x :call-site-instrumentation-plugin:test -x :modifiable-config-agent:test
• ./gradlew -p buildSrc spotlessCheck

[aalbertjay]

@bric3 CI on this fork PR is failing before checkout because dd-octo-sts does not receive OIDC variables for fork-originated workflows. Could you please mirror this to an internal DataDog/dd-trace-java branch, as you did for #12539 in #12592? The repository build check and focused local tests pass.