test: skip agent e2e when LLM budget is exhausted

[ling-senpeng13]

Summary

• register a JUnit extension across Java agent E2E tests through BaseTest
• convert only the provider's explicit API usage-limit failure into an aborted/skipped test
• preserve all unrelated LLM and workflow failures
• add focused tests for cause-chain detection, skip behavior, and unrelated-error propagation

Validation

• ./gradlew :e2e:test -Pe2e --tests LlmBudgetExhaustionExtensionTest
• git diff --check

Java counterpart to conductor-oss/python-sdk#445.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
see 1 file with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[kowser-orkes]

Lets move e2e tests to a proper package. Right now they are at the root.
My recommendation is org.conductoross.conductor.ai.e2e

[ling-senpeng13]

Lets move e2e tests to a proper package. Right now they are at the root. My recommendation is org.conductoross.conductor.ai.e2e

Sure. Let me do it in another PR to unblock the test