fix(core): rpc reload has old cache

[NNTin]

Description of the changes

When a cog is unregistered and re-registered, the RPC methods are being removed and added, but the JsonRpcMethod wrapper is storing a reference to the old method object from the original cog instance.

• Investigate why rpc_reload() in redbot/core/core_commands.py doesn't properly refresh module code
• The issue: _cleanup_and_refresh_modules() is called in rpc_load() but old method references may persist
• Fix the reload sequence to ensure modules are refreshed before re-reigstering RPC handlers
• Ensure bot.remove_cog() properly unregisters old RPC handlers before new ones are added

Have the changes in this PR been tested?

Yes, via tests
No, via manual reproduction of issue

[NNTin]

            # Call RPC handler and verify it now executes new code
            result = await new_handler()
>           assert result == "version_2", "RPC handler should execute new code after reload"
E           AssertionError: RPC handler should execute new code after reload
E           assert 'version_1' == 'version_2'
E             - version_2
E             ?         ^
E             + version_1
E             ?         ^

from https://github.com/Cog-Creators/Red-DiscordBot/actions/runs/19065280048/job/54454289643?pr=6628
I can now reproduce the problem

[NNTin]

The test with the version update was fixed in commit 9650a09 (?)
Issue was caching.

python -m pytest tests/core/test_rpc.py::test_rpc_handler_updates_on_reload -v -s --tb=short

Solving rpc reload via websocket, has the same root of error:

Before reload:
Original cog: 2280439307152
Original handler: 2280439127936
Original cog method: 2280439129536

After reload:
New cog: 2280439307152 ← SAME COG OBJECT!
New handler: 2280439127936 ← SAME HANDLER OBJECT!
New cog method: 2280360060864 ← DIFFERENT METHOD OBJECT!

Solving that was a mess. Month just started and my GitHub Copilot is already at 50% usage 😖