It's been a pain keeping the watchOS SDKs updated in the Xcode cipd bundles. We've needed to maintain a separate version of the depot_tools mac_toolchain.
Despite this, the newest bundle again had the watch SDK stripped out: https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8829667883431985473/+/u/run_ios_app_with_extensions_test/test_stdout

Instead of fixing that bug, let's remove the need for the watchOS SDK in tests. It's currently only used in ios_app_with_extensions_test to validate that an iOS app with a watch companion builds. See #51126 and #64674.

Avoid actually building the watch app by removing the watch app as a build dependency, and stop embedding the watch in the app bundle. Instead, validate via stdout that the tool detects the watch companion, and avoids adding the -sdk flag that used to prevent these kinds of apps from building. Build the app, but do not run on a simulator with a paired watch app.

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