[mono] Fix jit_mm mismatch in delegate trampoline creation for dynamic methods

[lewing]

Problem

mono_create_delegate_trampoline_info used a merged memory manager (class + method) to select which jit_mm->delegate_info_hash to insert into, but mono_jit_free_method used jit_mm_for_method (method-only) to look up and remove entries. When the merged mm differed from the method mm, cleanup would silently fail to remove the delegate_info_hash entry and could trigger the assertion at mini-runtime.c:3006:

g_assert (dpair->method == method);

Additionally, the two hash table insertions (delegate_info_hash and dyn_delegate_info_hash) used separate lock/unlock regions, creating a window where a concurrent mono_jit_free_method could see an inconsistent state — finding a dpair in dyn_delegate_info_hash that hadn't been fully set up yet, or missing one that was already in delegate_info_hash.

This manifests as a random assertion failure on WASM with AOT and threads enabled:

[MONO] * Assertion at mini-runtime.c:3007, condition '' not met

Fix

1. For dynamic methods, use jit_mm_for_method consistently (matching the cleanup path in mono_jit_free_method) instead of the merged memory manager.
2. Perform both hash table insertions (delegate_info_hash and dyn_delegate_info_hash) under a single lock to eliminate the partial-state window.

Fixes #120059

[Copilot]

Pull request overview

Fixes a Mono JIT runtime bookkeeping mismatch for delegate trampoline info associated with dynamic methods, ensuring the same MonoJitMemoryManager is used for both insertion and cleanup, and making the insertion atomic with respect to concurrent cleanup.

Changes:

• For dynamic methods, use jit_mm_for_method(method) (instead of a merged class+method memory manager) when selecting the delegate_info_hash owner.
• Insert into delegate_info_hash and dyn_delegate_info_hash under a single jit_mm lock to avoid transient partial state during concurrent mono_jit_free_method.

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[lewing]

/ba-g ios failures are infra