Revert obsolete parts of 'Android modifications to OkHttp'

Reverts parts of AOSP commit 36132b3c

This CL was created with the following command line:
$ git show --patch 36132b3c \
okhttp-urlconnection/src/main/java/com/squareup/okhttp/internal/huc/HttpsURLConnectionImpl.java \
okhttp-android-support/src/main/java/com/squareup/okhttp/internal/huc/JavaApiConverter.java \
| patch -R -p1

Test: Ran the following tests. The only failure was b/29095428
$ cts-tradefed run cts -c libcore.java.net.URLConnectionTest
$ cts-tradefed run cts -p android.core.tests.libcore.package.okhttp

Bug: 29633179
Change-Id: I2d4c3faea516eb586816f4445611f120691175e3