Wrap accounting breaker check in assertBusy (elastic#39211)

There may be situations where indices have not yet been closed from a Lucene
perspective, causing the breaker to not immediately be at 0

Relates to elastic#30290

Author: dakrone

test/framework/src/main/java/org/elasticsearch/test/InternalTestCluster.java

@@ -2413,9 +2413,15 @@ public void ensureEstimatedStats() {
                 final CircuitBreakerService breakerService = getInstanceFromNode(CircuitBreakerService.class, nodeAndClient.node);
                 CircuitBreaker fdBreaker = breakerService.getBreaker(CircuitBreaker.FIELDDATA);
                 assertThat("Fielddata breaker not reset to 0 on node: " + name, fdBreaker.getUsed(), equalTo(0L));
-                CircuitBreaker acctBreaker = breakerService.getBreaker(CircuitBreaker.ACCOUNTING);
-                assertThat("Accounting breaker not reset to 0 on node: " + name + ", are there still Lucene indices around?",
-                        acctBreaker.getUsed(), equalTo(0L));
+                try {
+                    assertBusy(() -> {
+                        CircuitBreaker acctBreaker = breakerService.getBreaker(CircuitBreaker.ACCOUNTING);
+                        assertThat("Accounting breaker not reset to 0 on node: " + name + ", are there still Lucene indices around?",
+                            acctBreaker.getUsed(), equalTo(0L));
+                    });
+                } catch (Exception e) {
+                    throw new AssertionError("Exception during check for accounting breaker reset to 0", e);
+                }
                 // Anything that uses transport or HTTP can increase the
                 // request breaker (because they use bigarrays), because of
                 // that the breaker can sometimes be incremented from ping
@@ -2430,7 +2436,7 @@ public void ensureEstimatedStats() {
                         assertThat("Request breaker not reset to 0 on node: " + name, reqBreaker.getUsed(), equalTo(0L));
                     });
                 } catch (Exception e) {
-                    fail("Exception during check for request breaker reset to 0: " + e);
+                    throw new AssertionError("Exception during check for request breaker reset to 0", e);
                 }
 
                 NodeService nodeService = getInstanceFromNode(NodeService.class, nodeAndClient.node);