[Unit tests] Decrease concurrency.

.config/nextest.toml

@@ -5,6 +5,8 @@ status-level = "skip"
 failure-output = "immediate-final"
 # Cancel test run on the first failure. Accounts for retries.
 fail-fast = true
+# Mark each test as requiring 2 threads. This avoids starvation (e.g., due to heavy tests that spawn additional threads).
+threads-required = 2
 
 junit = { path = "junit.xml" }
 

devtools/aptos-cargo-cli/src/lib.rs

@@ -457,7 +457,7 @@ fn run_targeted_compiler_v2_tests(
     Ok(())
 }
 
-/// Runs the targeted unit tests
+/// Runs the targeted unit tests!
 fn run_targeted_unit_tests(
     packages_to_test: Vec<String>,
     mut direct_args: Vec<String>,