[Gameplay] Inactive Heimerdinger turrets not damaged by Rift Herald

If Heimerdinger has an inactive turret within range of the Rift Herald, if the Herald is actively fighting, it will attack the turret but do no damage.

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Full set of my unresolved bug report threads:

• Match History still calls north team "Purple"
• Team Builder lobby doesn't dissolve if an invited player disconnects
• Zyra passive can't be fired with an unranked ability's key
• Ahri R should start cooldown upon death
• Targeted abilities sometimes fizzle if their target moves away
• Storm Shield relics on Crystal Scar can be displaced
• Orianna's Ball may return while distance indicator is still yellow
• "Enable HUD animations" does nothing; "Disable minimap movement" ignores some input
• Galio W doesn't provoke heal from Twitch passive
• Teemo passive prevents capture of a neutral Twisted Treeline altar
• Anivia passive doesn't trigger if killed by Razorfins
• Vilemaw death timer not appearing
• Item Set construction doesn't properly label items' map availability
• Removed items are still displayed in Item Sets
• Zyra passive on quick cast is erratic
• Zyra can use trinket while in passive
• Inactive Heimerdinger turrets not damaged by Rift Herald

I will be bumping these threads periodically, though in a way that avoids flooding.