BuffReminders: Improve Shaman Earth Shield reminder

[Harreks]

What does this PR do?

The Earth Shield buff reminder for shamans currently only checks for the self buff (id 383648) to remove the reminder, this change also adds the ally buff (id 974) to the check. If Elemental Orbit is talented it requires both buffs to be present, if its not talented it only looks for the ally buff.

Closes this discord request: https://discord.com/channels/585577383847788554/1529315739394379776

How was it tested?

12.1.0 live game. Tested in story mode raid with both Elemental Orbit talented and untalented and all possible combinations of buffs active and missing.

Checklist

• New settings default OFF (no behavior change without opt-in)
• Zero cost while disabled: no events registered, no polling, no hooks doing work, no frames built
• Cheap while enabled: event-driven (no polling, no timer-based logic, no per-frame allocations)
• No writes onto Blizzard-owned frames (weak-table pattern used); HookScript/hooksecurefunc only, never SetScript on Blizzard frames
• Tested in-game on live; no version gates or pre-Midnight APIs added