Remove legacy build pipeline from GitHub Actions

Summary:
After landing the diff to add a privacy manifest to IGListKit's SPM package, the `Carthage-Legacy-Lipo-Binaries` build pipeline started failing.

Looking into it, this is because in order to support bundled resources in a Swift Package (Which is necessary to staple the manifest to the framework), the build tools version must be set at Swift 5.3. Meanwhile, the legacy build pipeline requires Xcode 11 in order to support the `lipo` command, and that one only goes up to Swift build tools 5.2.

The reason why XCFramework superseded fat binaries is because fat binaries may only have 1 slice of any given architecture in it (eg arm64). And with Apple Silicon, 2 arm64 slices (One for the iOS Simulator, and one for iOS hardware) are basically the norm now.

With that in mind, now that the Apple Silicon transition is complete, and in order to properly support privacy manifests, I think it's time we retire the `lipo` build pipeline in favour of supporting just the XCFramework route.

Reviewed By: benhgreen

Differential Revision: D55005596

fbshipit-source-id: ad9bc9512160065dfc699cd05d2bb1e92883e957

.github/workflows/CI.yml

@@ -181,18 +181,6 @@ jobs:
       - name: Carthage build framework
         run: carthage build --no-skip-current --use-xcframeworks
 
-  Carthage-Legacy-Lipo-Binaries:
-    name: Verify Carthage build lipo binaries
-    runs-on: macos-11
-    env:
-      DEVELOPER_DIR: /Applications/Xcode_11.7.app
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v3
-
-      - name: Carthage build framework
-        run: carthage build --no-skip-current
-
   Build-Examples:
     name: Build Examples and UI tests.
     runs-on: macos-13