Remove dep from sui-core to sui-test-cluster (MystenLabs#18539)

## Description 

depending on sui-test-cluster means depending on everything. sui-core
should not depend on it.
Move the impacted test to e2e tests.

## Test plan 

CI

---

## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:

crates/sui-core/Cargo.toml

@@ -111,7 +111,6 @@ serde-reflection.workspace = true
 serde_yaml.workspace = true
 num-bigint = "0.4.4"
 
-test-cluster.workspace = true
 move-symbol-pool.workspace = true
 
 sui-test-transaction-builder.workspace = true

crates/sui-core/src/overload_monitor.rs

@@ -18,10 +18,6 @@ use tokio::time::sleep;
 use tracing::{debug, info};
 use twox_hash::XxHash64;
 
-#[cfg(test)]
-#[path = "unit_tests/overload_monitor_tests.rs"]
-pub mod overload_monitor_tests;
-
 #[derive(Default)]
 pub struct AuthorityOverloadInfo {
     /// Whether the authority is overloaded.