isolate: set AllowDanglingSymlinks
isolate: set AllowDanglingSymlinks

This is for https://crbug.com/1237607#c26

Bug: 1237607
Change-Id: Ie985d9d4eb65e87bcff7d4b3d9a9f0372693f685
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/3109508
Auto-Submit: Takuto Ikuta <71927f930fca81015e0f496c65cd126ab1a692e3@chromium.org>
Reviewed-by: Yoshisato Yanagisawa <5d95c5c75e3d691d9c77888fff4498e04f8b7157@google.com>
Commit-Queue: Takuto Ikuta <71927f930fca81015e0f496c65cd126ab1a692e3@chromium.org>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go