fix: let preferUnplugged override pkg.conditions

[jonaskuske]

What's the problem this PR addresses?

fix #4749

How did you fix it?

Check manifest.preferUnplugged before checking pkg.conditions so it takes precedence

Checklist

• I have read the Contributing Guide.

• I have set the packages that need to be released for my changes to be effective.

• I will check that all automated PR checks pass before the PR gets reviewed.

[merceyz]

When conditions is set the contents of the manifest depends on which system you're on so this change isn't safe.

berry/packages/yarnpkg-core/sources/Cache.ts

Lines 166 to 185 in 15c481d

	// Conditional packages may not be fetched if they're intended for a
	// different architecture than the current one. To avoid having to be
	// careful about those packages everywhere, we instead change their
	// content to that of an empty in-memory package.
	//
	// This memory representation will be wrapped into an AliasFS to make
	// it seem like it actually exist on the disk, at the location of the
	// cache the package would fill if it was normally fetched.
	const makeMockPackage = () => {
	const zipFs = new ZipFS(null, {libzip});
	const rootPackageDir = ppath.join(PortablePath.root, structUtils.getIdentVendorPath(locator));
	zipFs.mkdirSync(rootPackageDir, {recursive: true});
	zipFs.writeJsonSync(ppath.join(rootPackageDir, Filename.manifest), {
	name: structUtils.stringifyIdent(locator),
	mocked: true,
	});
	return zipFs;
	};

[jonaskuske]

@merceyz I'm not sure whether you mean that the general change of respecting preferUnplugged over conditions again is unsafe and not compatible with Yarn's goals, or that my implementation is unsafe and needs to be fixed?