Inherit CODE_SIGN_STYLE in Keystone—makes it Manual

[mokagio]

This addresses a provisioning settings that would have resulting in targets using the framework failing to build for distribution.

Keystone has conflicting provisioning settings.
Keystone is automatically signed, but code signing identity Apple Development: Created via API (886NX39KP6) has been manually specified.
Set the code signing identity value to "Apple Development" in the build settings editor, or switch to manual signing in the Signing & Capabilities editor.

Before

After

These are the same settings WordPressAuthenticator uses.

I noticed this while troubleshooting #24374

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 25.9. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

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[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Configuration	Release-Alpha
	Build Number	26988
	Version	PR #24377
	Bundle ID	com.jetpack.alpha
	Commit	498f29e
	Installation URL	0rqjjnbh41g8o

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[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Configuration	Release-Alpha
	Build Number	26988
	Version	PR #24377
	Bundle ID	org.wordpress.alpha
	Commit	498f29e
	Installation URL	2t274pqlv08i0

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.