Janitorial: Disparate cleanup tasks (#40200)

* Remove Phan suppression now that PHPDoc is correct in supported WP versions

* Remove WP 6.5 polyfill (see #38428)

* Remove is_callable check for wp_trigger_error()

* setMethods → onlyMethods

* static → const property

* Add type hinting

* Throw exception instead of triggering deprecation notice

* Remove now-unneeded CSS

* Updated comment

* Add future todo

* Remove fallbacks

* Add changelogs

* Remove composer downgrade logic

* CRM requires PHP 7.4 already

* Super Cache has previously required WP 6.5

* Vaultpress has previous required WP 5.2

* Get realpath of temp dir

* Fix changelogger tests

* Add changelogs

* Fix typo

* Adjust comment

* Simplify logic

* See if this sates tests

* Jetpack::is_connection_ready has been around in its current state since JP 9.7

* Remove checks for more long-present calls

* Clean up Phan suppressions

* Update changelog

Co-authored-by: Brad Jorsch <[email protected]>

* Update changelog

Co-authored-by: Brad Jorsch <[email protected]>

* Remove old comment

---------

Co-authored-by: Brad Jorsch <[email protected]>

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/11897114078

Upstream-Ref: Automattic/jetpack@d4ff610

composer.json

@@ -5,17 +5,17 @@
 	"license": "GPL-2.0-or-later",
 	"require": {
 		"php": ">=7.2",
-		"automattic/jetpack-assets": "^3.0.0",
+		"automattic/jetpack-assets": "^4.0.0-alpha",
 		"automattic/jetpack-connection": "^6.0.1-alpha",
 		"automattic/jetpack-constants": "^3.0.0",
 		"automattic/jetpack-plans": "^0.5.0",
 		"automattic/jetpack-redirect": "^3.0.0",
-		"automattic/jetpack-status": "^5.0.0",
+		"automattic/jetpack-status": "^5.0.1-alpha",
 		"automattic/jetpack-sync": "^4.0.0"
 	},
 	"require-dev": {
 		"yoast/phpunit-polyfills": "^1.1.1",
-		"automattic/jetpack-changelogger": "^5.0.0",
+		"automattic/jetpack-changelogger": "^5.1.0-alpha",
 		"automattic/wordbless": "@dev"
 	},
 	"suggest": {