Preserve ammo linkage on zone unload

[robob27]

Summary

Bugfixes "Preserve ammo belt linkages when unloading with zones"

Purpose of change

Fixes #60310

Describe the solution

As a quick fix for stable, and as suggested by @RenechCDDA, copies the code that is responsible for preserving ammo belt linkages from unload_activity_actor::unload (the player manually unloading) to other code that is responsible for unloading using zones so that the linkages will also be preserved there. An ideal fix would be more DRY.

The copied code is from:

Cataclysm-DDA/src/activity_actor.cpp

Lines 2929 to 2936 in 57c865e

	// remove the belt linkage
	if( it.is_ammo_belt() ) {
	if( it.type->magazine->linkage ) {
	item link( *it.type->magazine->linkage, calendar::turn, qty );
	if( who.add_or_drop_with_msg( link, true ) ) {
	actually_unloaded = true;
	}
	}

I made some small modifications to spawn the linkages on the tile the unloaded item is on and not show the disassembly message so it doesn't spam them if many belts get unloaded back to back.

Describe alternatives you've considered

Testing

• Spawn some ammo belts
• Put them in an unload zone
• Unload them using SHIFT+O
• Check that the ammo linkages don't disappear and that the number of linkages created = the number of ammo unloaded
• The linkages should be unloaded on the tile that the ammo belt was on
• The ammo belt should be removed if it's empty

Additional context

[robob27]

After I got the test setup somewhat properly it didn't fail a single time locally but of course it fails in CI and I can't replicate the failure. It seems like after

complete_activity( dummy, unload_loot_activity_actor() );

the items are not always available on the map right away, so it can fail. Not sure what the best fix is for that but it's probably real simple. I gotta sleep but this gets this issue most of the way there, I think!

[robob27]

The test is still passing 100% of the time locally and failing 100% of the time on the "GCC 9, Curses, LTO" check (I assume my latest commit won't change this). I don't understand 🙃. Otherwise, everything seems to be working as described in the testing steps. I'll probably have to leave this as is, I'm out of ideas for now. Please feel free to ping me here or on the discord if anyone has any suggestions to fix the test, or drop it or whatever works best for stable release 🚀

[robob27]

Current failure is from an unrelated test, I think this is probably good to go.