Refactor Task/Counter Classification for Runtime-Managed Tasks

[ShangkunLi]

In this PR:

• Split ClassifyTaskAndCounterPass into two phases: counter classification first, runtime-managed task identification second.
• Replaced old symbol_dynamic semantics with regular_dynamic counter dynamism.
• Mark tasks as runtime_managed only when they contain regular-dynamic counters and no loop-carried dependence pattern.
• Updated pass documentation and related FileCheck expectations.