Remove jcenter plugin (#2001)

Summary:
Closes https://github.com/facebook/flipper/pull/2001

Pull Request resolved: https://github.com/facebook/flipper/pull/2036

Test Plan:
- ./gradle :android:assembleDebug
- CI

Reviewed By: fabiomassimo

Differential Revision: D26888718

Pulled By: passy

fbshipit-source-id: ea59c6e51bda176f479d420b9955c994fea770bc

build.gradle

@@ -9,7 +9,6 @@ buildscript {
     repositories {
         google()
         mavenCentral()
-        jcenter()
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:4.1.2'
@@ -21,7 +20,6 @@ buildscript {
 
 plugins {
     id 'de.undercouch.download' version '4.0.1'
-    id 'com.jfrog.bintray' version '1.8.4'
     id 'com.github.dcendents.android-maven' version '2.1'
     id 'com.github.ben-manes.versions' version '0.28.0'
 }