Reset frontier search state before directly tagging a root in ReferenceChainTestSeamsTest

An earlier test can leave the shared FrontierTable full/tiny
(shouldReportAbandonedSearchOnTinyFrontierCap deliberately caps it at 1);
without resetting first, tagAsReferenceChainRoot0()'s insert() fails
deterministically.

Author: jbachorik

ddprof-test/src/test/java/com/datadoghq/profiler/referencechains/ReferenceChainTestSeamsTest.java

@@ -105,6 +105,13 @@ public void shouldReconstructChainForDirectlyTaggedRoot() {
     assumeDebugBuild();
     JavaProfiler.resetKlassPopulationForTest0();
     JavaProfiler.setGcGenerationsEnabled0(true);
+    // Guards against inheriting a FrontierTable an earlier test in this same, no-forkEvery
+    // JVM left permanently full/tiny - e.g. ReferenceChainTrackingTest's own
+    // shouldReportAbandonedSearchOnTinyFrontierCap deliberately drives the shared table to
+    // framecap=1 and leaves it that way. Same defensive pattern that class's own tests already
+    // use (see its header comment); without it, tagAsReferenceChainRoot0()'s insert() below can
+    // fail against a table this test never sized itself.
+    JavaProfiler.resetReferenceChainSearchForTest0();
 
     Object target = new Object();