External Libraries: Revert [47603].

With the Docker image for PHP 7.4 updated to stable version, this should no longer be necessary.

See https://github.com/WordPress/wpdev-docker-images/pull/26

Props ocean90.
Fixes #49945.
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git-svn-id: https://core.svn.wordpress.org/trunk@47379 1a063a9b-81f0-0310-95a4-ce76da25c4cd