Add some flags to generate_android_bp.py to make the AOSP match the
ANGLE build flags, which makes the CQ testing more relevant and reduces
the ANGLE APK size.   Additionally, disable various GN args that are no
longer required (GL, ESSL, HSSL).   Together, this reduces the ANGLE APK
size in AOSP from 22.2MB to 16.7MB.

This CL also makes some fixes to roll_aosp.sh that are suggested by
"Shell Scipt".

Bug: b/189125396
Test: manual verification
Change-Id: Iea33de799a00ffff182cf028a6998e1ef01a00e1
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2912933Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Tim Van Patten <timvp@google.com>