Fix/autoloader guard allows same plugin in mu plugins

[darssen]

Changes proposed in this Pull Request:

• Changed check in autoloader guard to consider the comparison between current and latest plugin to be done using plugin data instead of the plugin path. p1660675242364729-slack-CDD9LQRSN 3543-gh-Automattic/vip-go-mu-plugins

Other information:

• [ ] Have you written new tests for your changes, if applicable?
• [ X ] Have you checked the E2E test CI results, and verified that your changes do not break them?

Jetpack product discussion

Does this pull request change what data or activity we track or use?

No.

Testing instructions:

• Install the same version of a plugin that uses Jetpack autoloader (e.g. Jetpack) inside mu-plugins (This can be done by copying the plugin folder into the mu-plugins folder and using a proxy PHP loader file as indicated here )
• Make sure the plugin is in active plugins.
• Try to navigate to the WP application.
• Prior to the changes, a Fatal Cannot declare class ... should appear. After the changes Fatal should not be present and application should be able to load normally.

[github-actions[bot]]

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