Remove unused Makefiles from React Native core

Summary:
This diff cleans up several Android Makefiles which we're not using anymore
as they've been replaced by CMake files.

There are still 3 Makefiles left, which I'm aiming to remove in the near future.

Changelog:
[Internal] [Changed] - Remove unused Makefiles from React Native core

Reviewed By: javache

Differential Revision: D36660902

fbshipit-source-id: 8afffac74d493616b0f9414567821cd69f4ef803

ReactAndroid/src/main/java/com/facebook/react/modules/blob/jni/Android.mk

@@ -1,26 +0,0 @@
-# Copyright (c) Meta Platforms, Inc. and affiliates.
-#
-# This source code is licensed under the MIT license found in the
-# LICENSE file in the root directory of this source tree.
-
-LOCAL_PATH := $(call my-dir)
-
-include $(CLEAR_VARS)
-
-LOCAL_MODULE := reactnativeblob
-
-LOCAL_SRC_FILES := $(wildcard $(LOCAL_PATH)/*.cpp)
-
-LOCAL_C_INCLUDES := $(LOCAL_PATH)
-
-LOCAL_CFLAGS += -fvisibility=hidden -fexceptions -frtti
-
-LOCAL_STATIC_LIBRARIES :=  libjsireact
-LOCAL_SHARED_LIBRARIES := \
-  libfb \
-  libfbjni \
-  libfolly_runtime \
-  libjsi \
-  libreactnativejni
-
-include $(BUILD_SHARED_LIBRARY)