Revert "Reland "Clipboard: Add test helper for portable type checks""

This reverts commit 3cf1cb8f.

Reason for revert: Tree closing failures

Original change's description:
> Reland "Clipboard: Add test helper for portable type checks"
>
> This is a reland of b65ee036
>
> This reland updates how URLs are checked on Macs. The trybot which
> failed on the original CL has been added to Cq-Include-Trybots.
>
> Original change's description:
> > Clipboard: Add test helper for portable type checks
> >
> > For portable types, reading from the clipboard involves both a check of
> > IsFormatAvailable() and ReadAvailableTypes(). This CL adds a helper
> > which does both of these checks, simplifying the code and reducing the
> > chances that new code will accidentally only check one of these
> > methods (see: https://crbug.com/1215137).
> >
> > For non-portable types, comments have been left to explain why this
> > helper is not used.
> >
> > Bug: 1241712, 1215137
> > Change-Id: I25f03a2d4c2559e688fbf26a06893cde4725d673
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3111332


> > Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
> > Reviewed-by: Darwin Huang <huangdarwin@chromium.org>
> > Commit-Queue: Austin Sullivan <asully@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#914517}
>
> Bug: 1241712, 1215137, 1242731
> Change-Id: I87c1397449fea42b866ecdd4dbd773771c770e4b
> Cq-Include-Trybots: luci.chromium.try:mac-official;luci.chromium.try:win-official
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3123739


> Commit-Queue: Marijn Kruisselbrink <mek@chromium.org>
> Auto-Submit: Austin Sullivan <asully@chromium.org>
> Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#917733}

Bug: 1241712, 1215137, 1242731
Change-Id: Ieeda57ef4bbc9156d22a3acfa9b065fd035f59f2
Cq-Include-Trybots: luci.chromium.try:mac-official;luci.chromium.try:win-official
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3138299
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Chong Gu <chonggu@google.com>
Owners-Override: Chong Gu <chonggu@google.com>
Cr-Commit-Position: refs/heads/main@{#917742}