Reland "Move resource request creation into PlusAddressHttpClientImpl helper."

This reverts commit 44855f4d16aa781fb2b0f49d64c598c4f11a5032.

Reason for revert: Moved relevant code out of DCHECKs again

Original change's description:
> Revert "Move resource request creation into PlusAddressHttpClientImpl helper."
>
> This reverts commit 506f4ec64fec5b0f1c5cde7a665777955fa53139.
>
> Reason for revert: Appears to be causing components_unittest
> failures.
>
> Original change's description:
> > Move resource request creation into PlusAddressHttpClientImpl helper.
> >
> > This CL contains no functionality changes - it just removes a bit of
> > code duplication.
> >
> > Bug: 322279583
> > Change-Id: I5e98862e389fdcab5a69c7cbcc6e24d380349d7d
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5763404
> > Auto-Submit: Jan Keitel <jkeitel@google.com>
> > Commit-Queue: Timofey Chudakov <tchudakov@google.com>
> > Reviewed-by: Timofey Chudakov <tchudakov@google.com>
> > Cr-Commit-Position: refs/heads/main@{#1338443}
>
> Bug: 322279583
> Change-Id: Ife660c203a95d369768deb5631a707b6ff120714
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5769751
> Owners-Override: Ian Vollick <vollick@google.com>
> Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> Commit-Queue: Ian Vollick <vollick@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1338472}

Bug: 322279583
Change-Id: Ib1c4855493150edd2317a040aa7b3816aacf48f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5772751
Auto-Submit: Jan Keitel <jkeitel@google.com>
Commit-Queue: Timofey Chudakov <tchudakov@google.com>
Commit-Queue: Jan Keitel <jkeitel@google.com>
Reviewed-by: Timofey Chudakov <tchudakov@google.com>
Cr-Commit-Position: refs/heads/main@{#1338914}