Revert "Roll Fuchsia SDK from ea00f9dcafd5 to 469421287ef1"

This reverts commit 900ffcbd.

Reason for revert: Roll introduced significant netstack regression (though things were already flaky before that).

Original change's description:
> Roll Fuchsia SDK from ea00f9dcafd5 to 469421287ef1
>
>
> The AutoRoll server is located here: https://autoroll.skia.org/r/fuchsia-sdk-chromium-autoroll
>
> Documentation for the AutoRoller is here:
> https://skia.googlesource.com/buildbot/+/master/autoroll/README.md
>
> If the roll is causing failures, please contact the current sheriff, who should
> be CC'd on the roll, and stop the roller if necessary.
>
>
> CQ_INCLUDE_TRYBOTS=luci.chromium.try:fuchsia-arm64-cast;luci.chromium.try:fuchsia-x64-cast
> TBR=cr-fuchsia+bot@chromium.org
>
> Change-Id: Ifab9496a837c590c6ca525402d0c24eed4aa0f9c
> Reviewed-on: https://chromium-review.googlesource.com/c/1347081
> 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@{#610293}

Bug: 908125
Change-Id: I168b641b747a5f909ef8dd0296bffb9fe898a5a0
Cq-Include-Trybots: luci.chromium.try:fuchsia-arm64-cast;luci.chromium.try:fuchsia-x64-cast
Reviewed-on: https://chromium-review.googlesource.com/c/1351454
Commit-Queue: Wez <wez@chromium.org>
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Reviewed-by: Fabrice de Gans-Riberi <fdegans@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610947}

build/fuchsia/linux.sdk.sha1

-9a796e9c3e778df5e4886380342b139188ba33be
+ea00f9dcafd5747a3ed871b428588e02bace859b
\ No newline at end of file

build/fuchsia/mac.sdk.sha1

-e9fbfaa2c9272be20f4c6e95c3e865a59c0e8332
+68cace884bb6eff292290c150e572dad6ccd37d3
\ No newline at end of file