Revert "[Reland] Pass the credentials mode to the download service."

This reverts commit 12da8094.

Reason for revert: Compile failure https://cr-buildbucket.appspot.com/build/8838078851703480065

Original change's description:
> [Reland] Pass the credentials mode to the download service.
>
> The default is still 'Allow' which will not affect any existing download
> clients, however the clients will be able to customize the credentials
> mode as needed.
>
> The CL was reverted in https://chromium-review.googlesource.com/c/chromium/src/+/3110756.
> Compilation error: https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket/8838358063796181409/+/u/compile/raw_io.output_failure_summary_
>
> Please review from Patchset 1 to see extra changes
>
> Bug: 1239709
> Change-Id: I486388759928ca503bec7ef17222a1fe53cd94b4
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3113020


> Reviewed-by: Xing Liu <xingliu@chromium.org>
> Reviewed-by: Reilly Grant <reillyg@chromium.org>
> Auto-Submit: Rayan Kanso <rayankans@chromium.org>
> Commit-Queue: Reilly Grant <reillyg@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#914449}

Bug: 1239709
Change-Id: I6ef6ee7e6e94d7f269db0b0a5ffb856565f43714
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3114777


Auto-Submit: Kristi Park <kristipark@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Kristi Park <kristipark@google.com>
Reviewed-by: Travis Skare <skare@chromium.org>
Owners-Override: Kristi Park <kristipark@google.com>
Cr-Commit-Position: refs/heads/main@{#914514}