Clean up boilerplate .gitattributes (#48802)

Add a lot of generic tooling `production-excludes` entries to the
monorepo root `.gitattributes`, and remove them from project
`.gitattributes`.

Also, have the mirror build always generate a `.gitattributes` that sets
`export-ignore` for `.git*` files, and additionally strip the setting of
any `production-include` and `production-exclude` attributes in the
mirror copy.

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/25877340776

Upstream-Ref: Automattic/jetpack@bf1983d

Author: anomiex

.gitattributes

@@ -1,30 +1,2 @@
-# Files not needed to be distributed in the package.
-.gitattributes    export-ignore
-.github/          export-ignore
-package.json      export-ignore
-
-# Files to include in the mirror repo, but excluded via gitignore
-# Remember to end all directories with `/**` to properly tag every file.
-# /src/js/example.min.js  production-include
-/src/**/*.min.css production-include
-/src/**/*.rtl.css production-include
-dist/**           production-include
-build/**          production-include
-
-# Files to exclude from the mirror repo, but included in the monorepo.
-# Remember to end all directories with `/**` to properly tag every file.
-.gitignore               production-exclude
-babel.config*            production-exclude
-changelog/**             production-exclude
-.phpcs.dir.xml           production-exclude
-tests/**                 production-exclude
-tools/**                 production-exclude
-.phpcsignore             production-exclude
-/src/dashboard/**/*.js   production-exclude
-/src/dashboard/**/*.scss production-exclude
-/src/blocks/**/*.js      production-exclude
-/src/blocks/**/*.scss    production-exclude
-tsconfig.json            production-exclude
-declarations.d.ts        production-exclude
-global.d.ts              production-exclude
-blueprints/**            production-exclude
+# Automatically generated rules.
+/.git*	export-ignore

composer.json

@@ -5,25 +5,25 @@
 	"license": "GPL-2.0-or-later",
 	"require": {
 		"php": ">=7.2",
-		"automattic/jetpack-blocks": "^3.3.1",
-		"automattic/jetpack-assets": "^4.3.36",
-		"automattic/jetpack-wp-build-polyfills": "^0.1.8",
-		"automattic/jetpack-connection": "^8.3.5",
-		"automattic/jetpack-device-detection": "^3.4.1",
+		"automattic/jetpack-blocks": "^3.3.2-alpha",
+		"automattic/jetpack-assets": "^4.3.37-alpha",
+		"automattic/jetpack-wp-build-polyfills": "^0.1.9-alpha",
+		"automattic/jetpack-connection": "^8.3.6-alpha",
+		"automattic/jetpack-device-detection": "^3.4.2-alpha",
 		"automattic/jetpack-external-connections": "^0.1.28-alpha",
-		"automattic/jetpack-jwt": "^0.2.3",
-		"automattic/jetpack-logo": "^3.0.6",
-		"automattic/jetpack-plans": "^0.11.5",
-		"automattic/jetpack-status": "^6.1.3",
-		"automattic/jetpack-sync": "^4.38.1",
-		"automattic/jetpack-admin-ui": "^0.8.4",
-		"automattic/jetpack-wp-abilities": "^0.1.0"
+		"automattic/jetpack-jwt": "^0.2.4-alpha",
+		"automattic/jetpack-logo": "^3.0.7-alpha",
+		"automattic/jetpack-plans": "^0.11.6-alpha",
+		"automattic/jetpack-status": "^6.1.4-alpha",
+		"automattic/jetpack-sync": "^4.38.2-alpha",
+		"automattic/jetpack-admin-ui": "^0.8.5-alpha",
+		"automattic/jetpack-wp-abilities": "^0.1.1-alpha"
 	},
 	"require-dev": {
 		"yoast/phpunit-polyfills": "^4.0.0",
-		"automattic/jetpack-connection": "^8.3.5",
+		"automattic/jetpack-connection": "^8.3.6-alpha",
 		"automattic/jetpack-test-environment": "@dev",
-		"automattic/phpunit-select-config": "^1.0.5",
+		"automattic/phpunit-select-config": "^1.0.6-alpha",
 		"automattic/wp-feature-api": "@dev"
 	},
 	"suggest": {