fix(test): isolate health tests from minimal-response env var race (#4702)

Three health handler tests assert on payload fields (degradedReasons,
details) that are absent when RUSTFS_HEALTH_MINIMAL_RESPONSE_ENABLE is
true. The minimal-mode sibling test sets that env var via
temp_env::with_var, which leaks across parallel test threads.

Wrap the three affected tests with their own with_var guard pinning the
env var to false so they are deterministic regardless of thread order.

rustfs/src/admin/handlers/health.rs

@@ -88,6 +88,7 @@ impl Operation for HealthCheckHandler {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use serial_test::serial;
     use temp_env::with_var;
 
     #[test]
@@ -285,6 +286,7 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_build_health_payload_minimal_mode_returns_status_and_ready_only() {
         let health = health_check_state(true, false, true, true, HealthProbe::Readiness);
         with_var(rustfs_config::ENV_HEALTH_MINIMAL_RESPONSE_ENABLE, Some("true"), || {
@@ -309,7 +311,9 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_build_health_payload_includes_degraded_reasons() {
+        with_var(rustfs_config::ENV_HEALTH_MINIMAL_RESPONSE_ENABLE, Some("false"), || {
             let health = health_check_state(false, false, false, true, HealthProbe::Readiness);
             let payload = build_health_payload(HealthPayloadContext {
                 health,
@@ -323,6 +327,7 @@ mod tests {
                 include_dependency_details: true,
             });
             assert_eq!(payload["degradedReasons"][0], "storage_and_iam_unavailable");
+        });
     }
 
     #[test]
@@ -343,7 +348,9 @@ mod tests {
     }
 
     #[test]
+    #[serial]
     fn test_build_health_response_parts_get_includes_payload() {
+        with_var(rustfs_config::ENV_HEALTH_MINIMAL_RESPONSE_ENABLE, Some("false"), || {
             let report = crate::server::DependencyReadinessReport {
                 readiness: crate::server::DependencyReadiness {
                     storage_ready: false,
@@ -360,10 +367,13 @@ mod tests {
             assert_eq!(payload["status"], "degraded");
             assert_eq!(payload["ready"], false);
             assert_eq!(payload["degradedReasons"][0], "storage_quorum_unavailable");
+        });
     }
 
     #[test]
+    #[serial]
     fn test_build_health_response_parts_readiness_marks_kms_not_ready() {
+        with_var(rustfs_config::ENV_HEALTH_MINIMAL_RESPONSE_ENABLE, Some("false"), || {
             let report = crate::server::DependencyReadinessReport {
                 readiness: crate::server::DependencyReadiness {
                     storage_ready: true,
@@ -373,13 +383,20 @@ mod tests {
                 },
                 degraded_reasons: Vec::new(),
             };
-        let parts =
+            let parts = build_health_response_parts(
-            build_health_response_parts(Method::GET, HealthProbe::Readiness, Some(&report), "rustfs-endpoint", None, Some(false));
+                Method::GET,
+                HealthProbe::Readiness,
+                Some(&report),
+                "rustfs-endpoint",
+                None,
+                Some(false),
+            );
             assert_eq!(parts.status_code, StatusCode::SERVICE_UNAVAILABLE);
             let payload = parts.payload.expect("GET should include payload");
             assert_eq!(payload["ready"], false);
             assert_eq!(payload["details"]["lock"]["ready"], true);
             assert_eq!(payload["details"]["kms"]["ready"], false);
             assert_eq!(payload["degradedReasons"][0], "kms_not_ready");
+        });
     }
 }