[iOS] Remove unnecessary CODE_SIGN_IDENTITY

ios/jitsi-meet-react.xcodeproj/project.pbxproj

 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CODE_SIGN_ENTITLEMENTS = "jitsi-meet-react.entitlements";
-				CODE_SIGN_IDENTITY = "iPhone Developer";
 				CURRENT_PROJECT_VERSION = 1;
 				DEAD_CODE_STRIPPING = NO;
 				ENABLE_BITCODE = NO;