Remove unused `release_management_in_ci.rb` lanes

[mokagio]

We no longer need repo-level automation to trigger release lanes. We have a dedicated internal app to do so. Keeping the lanes here would be more of a liability in terms of code that never gets used and is bound to become out-of-date.

In the rare occasion where one might need to trigger those builds manually, it can be done via the Buildkite GUI or API directly.

To verify they are unused I run git grep -e 'trigger_.*_in_ci', which returned only the lane declarations. Of course, this does not guarantee there are no references outside of the repo, but based on my understanding of our Automation I think it's safe to assume there are none. (But just to be sure, I grepped our backend codebase for _in_ci, and got no results.)

See also conversation at https://github.com/Automattic/simplenote-ios/pull/1655#discussion_r1753900531

Regression Notes

1. Potential unintended areas of impact – N.A.
2. What I did to test those areas of impact (or what existing automated tests I relied on) – N.A.
3. What automated tests I added (or what prevented me from doing so) – N.A.

---

PR submission checklist:

• [x] I have completed the Regression Notes.
• [x] I have considered adding unit tests for my changes. N.A.
• [x] I have considered adding accessibility improvements for my changes. N.A.
• [x] I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary. N.A.

UI changes testing checklist: Not a UI PR.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress Alpha by scanning the QR code below to install the corresponding build.

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr23589-af5658a
	Version	25.3
	Bundle ID	org.wordpress.alpha
	Commit	af5658ad6fd61d18dbf49a500540f91466f2ebed
	App Center Build	WPiOS - One-Offs #10648

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[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack Alpha by scanning the QR code below to install the corresponding build.

	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr23589-af5658a
	Version	25.3
	Bundle ID	com.jetpack.alpha
	Commit	af5658ad6fd61d18dbf49a500540f91466f2ebed
	App Center Build	jetpack-installable-builds #9692

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[iangmaia]

@mokagio note that we'd also need to update the WPiOS Rv2 scenarios together with this. There's specific reference to these lanes and suggestions to run them again if something doesn't work.

I've also jinxed this update on this PR yesterday, I should've mentioned it here 😓 . I'm fine keeping this change only in this PR to make things more focused, though we have to remember to do the Rv2 changes together with it as well.

[iangmaia]

For the record: I've disabled auto-merge as we don't want to merge this without the required Rv2 changes.

[iangmaia]

@mokagio update: I've created an Android counterpart of this PR and the diff D161466-code with the corresponding changes for both iOS and Android.

[mokagio]

Thanks @iangmaia for wrangling the dependency tree and for the Android counterpart. I should have thought of that, but I clearly have an iOS bias 😳

[iangmaia]

@mokagio

but I clearly have an iOS bias 😳

It happened with me before, so I guess we all do to either platform 😅 FYI, I've landed D161466-code.