[7.1 Backport] -- Fix upload snackbar double-counting a single HEIC upload in Safari

[adamsilverstein]

Backports #80371 (merged as 88074b1) to the wp/7.1 branch. The automated cherry-pick failed with a conflict; see #80371 (comment).

Why

Fixes #80369 for WordPress 7.1: in Safari, uploading a single HEIC image showed "Uploading 2 media items" and made the snackbar math wrong for the rest of the session. The upload queue passes the file to the mediaUpload setting for transport, and the editor's progress tracking counted that hand-off as a second, independent upload. The queue now passes isTransportOnly: true on that call so lifecycle-managing consumers (progress tracking, save locking) don't handle the same file twice.

Conflict resolution

The only conflict was in packages/upload-media/CHANGELOG.md: trunk's Unreleased section contains the #80376 entries (GIF conversion guardrails and the cancelItem change), which are not on wp/7.1 - they belong to the separate open backport #80420. Resolved by keeping the wp/7.1 side and adding only this PR's Bug Fixes entry.

Verification

Every source file in this PR is byte-identical to trunk's state after #80371 merged - git diff 88074b15759 <backport-tip> is empty for the editor package files and the e2e spec, and the remaining upload-media differences are exactly the #80376 pieces that wp/7.1 does not have yet. The new editor media-upload unit tests and the upload-media store tests pass (52 tests).

[github-actions]

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Co-authored-by: adamsilverstein <adamsilverstein@git.wordpress.org>
Co-authored-by: swissspidy <swissspidy@git.wordpress.org>

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[github-actions]

Size Change: +15 B (0%)

Total Size: 7.72 MB

📦 View Changed

Filename	Size	Change
build/scripts/editor/index.min.js	499 kB	+5 B (0%)
build/scripts/upload-media/index.min.js	15.2 kB	+10 B (+0.07%)

_{compressed-size-action}

[github-actions]

Flaky tests detected in 43ab8f2.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/29613801820
📝 Reported issues:

• [Flaky Test] adds and activates a new tab when pressing Enter at the end of a tab label #80106 in /test/e2e/specs/editor/blocks/tabs.spec.js

[adamsilverstein]

@t-hamano this is another manual cherry pick to the 7.1 branch.

[t-hamano]

The only conflict was in packages/upload-media/CHANGELOG.md: trunk's Unreleased section contains the #80376 entries (GIF conversion guardrails and the cancelItem change), which are not on wp/7.1 - they belong to the separate open backport #80420. Resolved by keeping the wp/7.1 side and adding only this PR's Bug Fixes entry.

It is unfortunate that the automatic cherry-pick failed solely due to changelog file conflicts, requiring manual creation of a backport PR. I wish there were a way to resolve this automatically...

[t-hamano]

I just cherry-picked this PR to the release/23.6 branch to get it included in the next release: f49b47f