Site Health: Display auto-update properly for plugins that don't support auto-updates.

Properly filter auto_update_plugin when displaying the table.

This brings the changes from [48731] to the 5.5 branch.

Fixes #50822.
Props Gwendydd, pbiron, audrasjb, SergeyBiryukov, whyisjake.

Built from https://develop.svn.wordpress.org/branches/5.5@48732


git-svn-id: https://core.svn.wordpress.org/branches/5.5@48494 1a063a9b-81f0-0310-95a4-ce76da25c4cd