Revert "Changes to include fast app reinstall in chrome://flags."

This reverts commit 5a2d490901b78a58633f0c633187bd06fe2085b3.

Reason for revert: Suspect for failing unit_tests, https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/linux-chromeos-rel/20476

Original change's description:
> Changes to include fast app reinstall in chrome://flags.
> 
> Bug: 911427
> Change-Id: Ic33fd7507d36d0e847598722067ce64802718f9e
> Reviewed-on: https://chromium-review.googlesource.com/c/1484391
> Reviewed-by: Jenny Zhang <jennyz@chromium.org>
> Commit-Queue: Rob Schonberger <robsc@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#634884}

TBR=jennyz@chromium.org,robsc@chromium.org

Change-Id: I69637a4f4064131eedf57f18f9a27769cf70a4f9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 911427
Reviewed-on: https://chromium-review.googlesource.com/c/1484587
Reviewed-by: Kristi Park <kristipark@chromium.org>
Commit-Queue: Kristi Park <kristipark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634907}
3 files changed