Revert "Roll Fuchsia SDK from 0.20200604.3.1 to 0.20200608.3.3"

This reverts commit d6d5f4b8.

Reason for revert: Newer SDK appears to still have the pkgfs serve failure issue.

Original change's description:
> Roll Fuchsia SDK from 0.20200604.3.1 to 0.20200608.3.3
>
> If this roll has caused a breakage, revert this CL and stop the roller
> using the controls here:
> https://autoroll.skia.org/r/fuchsia-sdk-chromium-autoroll
> Please CC cr-fuchsia+bot@chromium.org on the revert to ensure that a human
> is aware of the problem.
>
> To report a problem with the AutoRoller itself, please file a bug:
> https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug
>
> Documentation for the AutoRoller is here:
> https://skia.googlesource.com/buildbot/+doc/master/autoroll/README.md
>
> Cq-Include-Trybots: luci.chromium.try:fuchsia-arm64-cast;luci.chromium.try:fuchsia-x64-cast
> Tbr: cr-fuchsia+bot@chromium.org
> Change-Id: I2dae0bc2cc21c19b6aae40ca81301aeec23add66
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2236327
> Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
> Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
> Cr-Commit-Position: refs/heads/master@{#776396}

TBR=chromium-autoroll@skia-public.iam.gserviceaccount.com,cr-fuchsia+bot@chromium.org

Change-Id: Ia7e28c98427e00efd671024db43c468da3614cef
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1092054
Cq-Include-Trybots: luci.chromium.try:fuchsia-arm64-cast;luci.chromium.try:fuchsia-x64-cast
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2235721
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776477}

build/fuchsia/linux.sdk.sha1

-0.20200608.3.3
+0.20200604.3.1

build/fuchsia/mac.sdk.sha1

-0.20200608.3.3
+0.20200604.3.1