Reland "emulator: Increase AVD ramsize to 4GB"

This reverts commit da96cf1bb99e1c0926ed8ea62713dbf5f0f7627b.

Reason for revert: Reland to see if it can mitigate the timeout issue
on chrome_public_test_apk.

Original change's description:
> Revert "emulator: Increase AVD ramsize to 4GB"
>
> This reverts commit 852a6a1c0b16e8c6ddd6eaa6bcf7fa3ae0945ad3.
>
> Reason for revert: Increasing RAM didn't help. Hence reverting.
>
> Original change's description:
> > emulator: Increase AVD ramsize to 4GB
> >
> > Bug: 345579530
> > Change-Id: I111ce08f150de34dbb4f32664ea5423d4951e7a5
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5630884
> > Commit-Queue: Renuga Nanjappan <rnanjappan@chromium.org>
> > Reviewed-by: Haiyang Pan <hypan@google.com>
> > Cr-Commit-Position: refs/heads/main@{#1314879}
>
> Bug: 345579530
> Change-Id: I87ce497ff077cb80c561d31c67bdf0a4667a9c40
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5641277
> Commit-Queue: Renuga Nanjappan <rnanjappan@chromium.org>
> Reviewed-by: Haiyang Pan <hypan@google.com>
> Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> Cr-Commit-Position: refs/heads/main@{#1316771}

Bug: 378750324
Change-Id: Id16080d0d80f3c4982f23e428885409ebd3ccf95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6014787
Reviewed-by: Renuga Nanjappan <rnanjappan@chromium.org>
Commit-Queue: Haiyang Pan <hypan@google.com>
Cr-Commit-Position: refs/heads/main@{#1382028}