Revert "Temporarily remove enable-websocket-auth-connection-reuse from about:flags"

This reverts commit 7e3874d48e23ea0ef6f1464763cfb08b48ce86d4.

Reason for revert: The flag has now been removed from the about:flags page on M68 where it doesn't work. Re-introduce it in M69 where it works.

Original change's description:
> Temporarily remove enable-websocket-auth-connection-reuse from about:flags
> 
> The M68 branch has a non-working implementation of the
> enable-websocket-auth-connection-reuse flag. In order to avoid the
> confusion of having a flag that works in some versions and not in
> others, temporarily remove the flag from about:flags.
> 
> Once the flag has been disabled in the M68 branch it will be re-enabled
> for M69 by reverting this CL.
> 
> BUG=423609
> 
> Change-Id: Id17ac18e13effcfd5bd946dc1fe0f1c70df96539
> Reviewed-on: https://chromium-review.googlesource.com/1090700
> Commit-Queue: Adam Rice <ricea@chromium.org>
> Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#566730}

TBR=ricea@chromium.org,yhirano@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 423609
Change-Id: Ifb83673ab8e6efaefbbc50e85b560b889fc160ad
Reviewed-on: https://chromium-review.googlesource.com/1107437
Reviewed-by: Adam Rice <ricea@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568744}
3 files changed