Fix hot/cold splitting (dotnet#96074)

Change dotnet#95836 removed a bit too much code, namely, a loop that set
`BBF_COLD` on newly determined cold blocks. Restore that loop.

Add some additional IG jump dumping.

Fixes dotnet#95946

src/coreclr/jit/emit.cpp

@@ -4297,19 +4297,34 @@ void emitter::emitDispJumpList()
                 printf(" -> %s", getRegName(jmp->idReg1()));
             }
             else
+#endif // TARGET_ARM64
             {
                 printf(" -> IG%02u", ((insGroup*)emitCodeGetCookie(jmp->idAddr()->iiaBBlabel))->igNum);
             }
-#else
-            printf(" -> IG%02u", ((insGroup*)emitCodeGetCookie(jmp->idAddr()->iiaBBlabel))->igNum);
+
+            if (jmp->idjShort)
+            {
+                printf(" (short)");
+            }
+
+            if (jmp->idjKeepLong)
+            {
+                printf(" (long)");
+            }
 
 #if defined(TARGET_XARCH)
             if (jmp->idjIsRemovableJmpCandidate)
             {
                 printf(" ; removal candidate");
             }
 #endif // TARGET_XARCH
-#endif // !TARGET_ARM64
+
+#if defined(TARGET_AMD64)
+            if (jmp->idjIsAfterCallBeforeEpilog)
+            {
+                printf(" ; after call before epilog");
+            }
+#endif // TARGET_AMD64
         }
         printf("\n");
         jmpCount += 1;

src/coreclr/jit/flowgraph.cpp

@@ -3279,6 +3279,11 @@ PhaseStatus Compiler::fgDetermineFirstColdBlock()
         }
     }
 
+    for (block = firstColdBlock; block != nullptr; block = block->Next())
+    {
+        block->SetFlags(BBF_COLD);
+    }
+
 EXIT:;
 
 #ifdef DEBUG