chore: revert changelog and release changes, keep test timeout update

[demeyerthom]

Fixes #

NEW FEATURES | UPGRADE NOTES | ENHANCEMENTS | BUG FIXES | EXPERIMENTS

[Copilot]

Pull request overview

Reverts previously committed release/changelog updates by removing the generated v1.21.2 entry from CHANGELOG.md and restoring the underlying dependency notes as Changie “unreleased” change fragments.

Changes:

• Remove v1.21.2 - 2026-04-03 section from CHANGELOG.md.
• Add multiple .changes/unreleased/*.yaml dependency entries so Changie can re-generate release notes later.
• Adjust early-history changelog content near 0.1.0 (currently introduces a duplicated entry that needs cleanup).

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
CHANGELOG.md	Removes v1.21.2 section; currently contains duplicated 0.1.0 sections.
.changes/unreleased/Dependency-20260403-115852.yaml	Adds unreleased dependency note (“Updated go version and dependencies”).
.changes/unreleased/Dependency-20260402-004504.yaml	Adds unreleased dependency note for GitHub Actions group bump.
.changes/unreleased/Dependency-20260101-200606.yaml	Adds unreleased dependency note for GitHub Actions group bump.
.changes/unreleased/Dependency-20260101-200140.yaml	Adds unreleased dependency note for Go group bump.
.changes/unreleased/Dependency-20251101-200604.yaml	Adds unreleased dependency note for git-auto-commit-action bump.
.changes/unreleased/Dependency-20251101-200139.yaml	Adds unreleased dependency note for Go group bump.

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[Copilot]

There are two consecutive ## 0.1.0 (2018-09-14) sections with overlapping content. This will render a duplicated version entry in the changelog; please remove one of them and keep a single, consistent 0.1.0 entry (either the plain bullets or the 'New resource:' format).

Suggested change

	* `commercetools_api_extension`
	* `commercetools_subscription`
	* `commercetools_project_settings`
	## 0.1.0 (2018-09-14)
	### Added