Stop checking CIPD packages exist on linux-386.

We no longer support linux-386 and there are no CIPD builders that build
packages for it.

R=tandrii@chromium.org
BUG=854300

Change-Id: Ibfefee828118c898432784c8ef3dd5894a28cfaa
Reviewed-on: https://chromium-review.googlesource.com/1110845
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>

PRESUBMIT.py

@@ -13,7 +13,7 @@ import os
 
 
 ENSURE_FILE_TEMPLATE = r'''
-$VerifiedPlatform linux-386 linux-amd64 linux-arm64 linux-armv6l linux-mips64
+$VerifiedPlatform linux-amd64 linux-arm64 linux-armv6l linux-mips64
 $VerifiedPlatform linux-ppc64 linux-ppc64le linux-s390x
 $VerifiedPlatform mac-amd64
 $VerifiedPlatform windows-386 windows-amd64

cipd_manifest.txt

@@ -2,7 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-$VerifiedPlatform linux-386 linux-amd64 linux-arm64 linux-armv6l linux-mips64
+$VerifiedPlatform linux-amd64 linux-arm64 linux-armv6l linux-mips64
 $VerifiedPlatform linux-ppc64 linux-ppc64le linux-s390x
 $VerifiedPlatform mac-amd64
 $VerifiedPlatform windows-386 windows-amd64