remove useless config in circle ci (#19980)

Summary:
The gradle path is unnecessary.
pass all current ci.
none
 [GENERAL] [INTERNAL] [CI] - remove useless config in circle ci.
Closes https://github.com/facebook/react-native/pull/19980

Differential Revision: D8700298

Pulled By: hramos

fbshipit-source-id: ed50cab035f0d78dc482023460692a2ce137fb48

.circleci/config.yml

@@ -176,7 +176,7 @@ aliases:
   - &configure-android-path
     name: Configure Environment Variables
     command: |
-      echo 'export PATH=${ANDROID_NDK}:~/react-native/gradle-2.9/bin:~/buck/bin:$PATH' >> $BASH_ENV
+      echo 'export PATH=${ANDROID_NDK}:~/buck/bin:$PATH' >> $BASH_ENV
       source $BASH_ENV
 
   - &install-android-packages