Remove Okhttp3 Android Proguard Rules (#30514)

Summary:
Remove proguard keep rules on okhttp3. The library already contains its own consumer proguard --> see https://square.github.io/okhttp/r8_proguard/

The keep rules will increase the final apk size of android app. Currently, there is no way to disable proguard rules from transitive dependencies ( https://issuetracker.google.com/issues/37073777). So any android app that use react native will also contains this proguard rules.

## Changelog

[Android] [Removed] - Remove okhttp3 proguard rules

Pull Request resolved: #30514

Test Plan: n/a

Reviewed By: mdvacca

Differential Revision: D25616704

Pulled By: fkgozali

fbshipit-source-id: eb0bcbc4ace398a55ce6902e34c17b030bb87130

ReactAndroid/proguard-rules.pro

@@ -55,13 +55,6 @@
 # hermes
 -keep class com.facebook.jni.** { *; }
 
-# okhttp
-
--keepattributes Signature
--keepattributes *Annotation*
--keep class okhttp3.** { *; }
--keep interface okhttp3.** { *; }
--dontwarn okhttp3.**
 
 # okio