[4.5] fix: Composer autoload.psr4

[kenjis]

Description
Follow-up #8005

• remove Config\\ from autoload.psr4

If we use this repository from appstarter, the Config files in app/Config/ in this repository are loaded first.

Checklist:

• Securely signed commits
• [] Component(s) with PHPDoc blocks, only if necessary or adds value
• [] Unit testing, with >80% coverage
• [] User guide updated
• [] Conforms to style guide

[kenjis]

This is a bug fix in 4.5. Please review.

[lonnieezell]

How does this affect those that do manual installs and don't use Composer?

[kenjis]

See composer.json in develop below. It is the same as this PR.

CodeIgniter4/composer.json

Lines 64 to 71 in efb3816

	"autoload": {
	"psr-4": {
	"CodeIgniter\\": "system/"
	},
	"exclude-from-classmap": [
	"**/Database/Migrations/**"
	]
	},

and the namespace CodeIgniter and Config are registered in AutoloadConfig. So they work without Composer autoloader.

CodeIgniter4/system/Config/AutoloadConfig.php

Lines 93 to 96 in 8b0752a

	protected $corePsr4 = [
	'CodeIgniter' => SYSTEMPATH,
	'Config' => APPPATH . 'Config',
	];