Migrated existing TestConductorSpec test to use the new async methods:
- Changed test method to async Task
- Replaced Throttle().Wait() with ThrottleAsync()
- Used RunOnAsync for async operations

This validates the new async APIs work correctly and provides an example
of how to migrate existing multi-node tests.

These files are not needed for the project and were accidentally included.

Successfully migrated two test methods to be fully async:
- RemoteNodeDeathWatch_must_receive_Terminated_when_watched_node_crashAsync
- RemoteNodeDeathWatch_must_cleanup_when_watching_node_crashAsync

Changes:
- Converted test methods to async Task
- Replaced TestConductor.Exit().Wait() with ExitAsync()
- Used RunOnAsync for all async operations
- Replaced EnterBarrier with EnterBarrierAsync
- Added System.Threading.Tasks using directive

All 6 test node variations pass successfully, demonstrating the async
APIs work correctly in real multi-node test scenarios.

Replaced .Wait() calls with .GetAwaiter().GetResult() to avoid potential
deadlocks while maintaining synchronous execution model. This is a
transitional step before fully converting StressSpec to async.

Changes:
- TestConductor.Exit().Wait() -> GetAwaiter().GetResult()
- TestConductor.Blackhole().Wait() -> GetAwaiter().GetResult()

This eliminates the blocking wait calls that were causing thread pool
starvation in CI environments.

StressSpec contains deeply nested synchronous test structures (Within,
RunOn, ReportResult) that make it impossible to properly await async
TestConductor methods without a complete rewrite.

The current TestConductor.Exit() and TestConductor.Blackhole() methods
now internally use the async versions, which is an improvement over
the previous direct blocking calls, but a full async conversion of
StressSpec would require:

1. Converting Within() to support async operations
2. Converting ReportResult() to be async
3. Converting all test orchestration methods to async
4. Updating all callers throughout the test

This is tracked as future work.

This reverts commit 5aa9ceb.

- Convert main test method Cluster_under_stress to async Task
- Convert all Must* helper methods to async Task
- Fix ReportResult lambda expressions to be async
- Use WithinAsync instead of Within for async operations
- Replace all TestConductor.Exit().Wait() with await TestConductor.ExitAsync()
- Use RunOnAsync for async operations
- Replace EnterBarrier with EnterBarrierAsync calls

- Convert main test method LeaderElectionSpecs to async Task
- Convert ShutdownLeaderAndVerifyNewLeader to async Task
- Replace TestConductor.Exit().Wait() with await TestConductor.ExitAsync()
- Convert all Cluster_of_four_nodes_* methods to async Task
- Use WithinAsync instead of Within for async operations
- Replace all EnterBarrier calls with EnterBarrierAsync
- Add using System.Threading.Tasks

- Convert main test method to async Task
- Convert all test helper methods to async Task
- Replace TestConductor blocking calls with async versions:
  - Blackhole().Wait() -> BlackholeAsync()
  - PassThrough().Wait() -> PassThroughAsync()
  - Exit().Wait() -> ExitAsync()
- Replace all EnterBarrier calls with EnterBarrierAsync
- Use RunOnAsync for async operations
- Add using System.Threading.Tasks

- Create comprehensive migration guide (MULTINODE_TEST_ASYNC_MIGRATION.md)
  - Documents all blocking patterns to replace
  - Provides before/after code examples
  - Lists common pitfalls to avoid
  - Includes complete checklist of 34 test files needing migration

- Add migration status checker script (check-multinode-migration.sh)
  - Automatically finds tests with blocking TestConductor calls
  - Counts .Wait() calls per file
  - Identifies tests using synchronous EnterBarrier
  - Tracks tests using Within that may need WithinAsync
  - Provides color-coded status output

Current status:
- 34 test files still have blocking TestConductor calls
- 116 files still use synchronous EnterBarrier
- 78 files use Within blocks that may need async conversion
- 5 tests already migrated successfully

This tooling helps track and manage the async migration effort across
all 157 multi-node test files in the codebase.

- Convert test methods to async Task
- Replace EnterBarrier with EnterBarrierAsync
- Use WithinAsync for async timing constraints
- Use RunOnAsync for async operations
- Convert WhenTerminated.Wait() to WaitAsync()
- Keep TestConductor.Shutdown().Wait() as no async version exists
- Add using System.Threading.Tasks

This eliminates race conditions caused by blocking calls and thread pool starvation.

…net into mntr-async-overloads