Fix Android Hermes Test (#29710)

Summary:
This PR fixes the Hermes/Android test failing in RNTester

## Changelog

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[Android] [Fixed] - Fixes Android/Hermes Test

Pull Request resolved: #29710

Test Plan:
On running the command `./gradlew packages:rn-tester:android:app:assembleRelease`

We get the following output:
![Screenshot 2020-08-20 at 6 46 02 PM](https://user-images.githubusercontent.com/29942790/90774641-6960ee80-e315-11ea-8e39-40e9de237ede.png)

Reviewed By: cpojer

Differential Revision: D23240948

Pulled By: rickhanlonii

fbshipit-source-id: 34ce1b6a203c7ef3af9b66b1cbc514edca1c19b6

packages/rn-tester/android/app/build.gradle

@@ -82,7 +82,7 @@ project.ext.react = [
     root: "$rootDir",
     inputExcludes: ["android/**", "./**", ".gradle/**"],
     composeSourceMapsPath: "$rootDir/scripts/compose-source-maps.js",
-    hermesCommand: "../../../node_modules/hermes-engine/%OS-BIN%/hermesc",
+    hermesCommand: "$rootDir/node_modules/hermes-engine/%OS-BIN%/hermesc",
     enableHermesForVariant: { def v -> v.name.contains("hermes") },
     jsRootDir: "$rootDir/RNTester",
     enableCodegen: System.getenv('USE_CODEGEN'),