Determine whether we can remove support for `projects/{}/{}/releases` endpoints

[szokeasaurusrex]

The project-tied releases endpoints (/projects/{}/{}/releases) seem to be supported only for compatibility with legacy self-hosted versions:

sentry-cli/src/api/mod.rs

Lines 682 to 696 in 1fd856c

	// for single project releases use the legacy endpoint that is project bound.
	// This means we can support both old and new servers.
	if release.projects.len() == 1 {
	let path = format!(
	"/projects/{}/{}/releases/",
	PathArg(org),
	PathArg(&release.projects[0])
	);
	self.post(&path, release)?
	.convert_rnf(ApiErrorKind::ProjectNotFound)
	} else {
	let path = format!("/organizations/{}/releases/", PathArg(org));
	self.post(&path, release)?
	.convert_rnf(ApiErrorKind::OrganizationNotFound)
	}

We should consider whether we still need this compatibility, and if not, we should deprecate and remove support

[linear]

CLI-182

[szokeasaurusrex]

The organization release endpoint is at least 9 years old; therefore, I think it is safe for us to remove support for projects/{}/{}/releases, as everything we can do at that endpoint, we should also be able to do at /organizations/{}/releases/

[szokeasaurusrex]

As adding a deprecation warning would not be super straightforward, and we would only be breaking compatibility with very old Sentry versions, I think it is reasonable to just remove. Let's just ensure we clearly define the self-hosted versions we support

[szokeasaurusrex]

To be removed in #2840