Remove CoocaPods support from layers example app (#35780)

examples/layers/ios/Flutter/Debug.xcconfig

 #include "Generated.xcconfig"
-#include "Pods/Target Support Files/Pods-Runner/Pods-Runner.debug.xcconfig"

examples/layers/ios/Flutter/Release.xcconfig

 #include "Generated.xcconfig"
-#include "Pods/Target Support Files/Pods-Runner/Pods-Runner.release.xcconfig"

examples/layers/ios/Podfile

-# Uncomment this line to define a global platform for your project
-# platform :ios, '9.0'
-
-if ENV['FLUTTER_FRAMEWORK_DIR'] == nil
-  abort('Please set FLUTTER_FRAMEWORK_DIR to the directory containing Flutter.framework')
-end
-
-target 'Runner' do
-  use_frameworks!
-
-  # Pods for Runner
-
-  # Flutter Pods
-  pod 'Flutter', :path => ENV['FLUTTER_FRAMEWORK_DIR']
-
-  if File.exists? '../.flutter-plugins'
-    flutter_root = File.expand_path('..')
-    File.foreach('../.flutter-plugins') { |line|
-      plugin = line.split(pattern='=')
-      if plugin.length == 2
-        name = plugin[0].strip()
-        path = plugin[1].strip()
-        resolved_path = File.expand_path("#{path}/ios", flutter_root)
-        pod name, :path => resolved_path
-      else
-        puts "Invalid plugin specification: #{line}"
-      end
-    }
-  end
-end
-
-post_install do |installer|
-  installer.pods_project.targets.each do |target|
-    target.build_configurations.each do |config|
-      config.build_settings['ENABLE_BITCODE'] = 'NO'
-    end
-  end
-end

examples/layers/ios/Runner.xcodeproj/project.xcworkspace/contents.xcworkspacedata

@@ -4,7 +4,4 @@
    <FileRef
       location = "group:Runner.xcodeproj">
    </FileRef>
-   <FileRef
-      location = "group:Pods/Pods.xcodeproj">
-   </FileRef>
 </Workspace>

examples/layers/ios/Runner.xcworkspace/contents.xcworkspacedata

@@ -4,7 +4,4 @@
    <FileRef
       location = "group:Runner.xcodeproj">
    </FileRef>
-   <FileRef
-      location = "group:Pods/Pods.xcodeproj">
-   </FileRef>
 </Workspace>