Remove duplicated use_hermes in RCTAppDelecate podspec (facebook#44299)

Summary:
remove duplicated use hermes variable in RCTAppDelecate podsec file.

Pull Request resolved: facebook#44299

Test Plan:
Default setup flow (ios)

## Changelog:
[Internal] [Changed] - Remove duplicated use hermes variable in RCTAppDelecate podsec file.

Reviewed By: cipolleschi

Differential Revision: D56693121

Pulled By: arushikesarwani94

fbshipit-source-id: 2bbe4090d94cadd128be9c5d233a63499f735e68

packages/react-native/Libraries/AppDelegate/React-RCTAppDelegate.podspec

@@ -21,7 +21,7 @@ folly_compiler_flags = folly_config[:compiler_flags]
 folly_version = folly_config[:version]
 
 is_new_arch_enabled = ENV["RCT_NEW_ARCH_ENABLED"] == "1"
-use_hermes =  ENV['USE_HERMES'] == nil || ENV['USE_HERMES'] == '1'
+use_hermes = ENV['USE_HERMES'] == nil || ENV['USE_HERMES'] == '1'
 
 new_arch_enabled_flag = (is_new_arch_enabled ? " -DRCT_NEW_ARCH_ENABLED" : "")
 is_fabric_enabled = true #is_new_arch_enabled || ENV["RCT_FABRIC_ENABLED"]
@@ -66,8 +66,6 @@ Pod::Spec.new do |s|
   }
   s.user_target_xcconfig   = { "HEADER_SEARCH_PATHS" => "\"$(PODS_ROOT)/Headers/Private/React-Core\""}
 
-  use_hermes = ENV['USE_HERMES'] == nil || ENV['USE_HERMES'] == "1"
-
   s.dependency "React-Core"
   s.dependency "RCT-Folly", folly_version
   s.dependency "RCTRequired"