Remove archive php.tar.xz from final images

[vladislavzl]

The php.tar.xz archive contains tests that are detected as malware.
Like this:
layer.tar//usr/src/php.tar.xz//xz//php-8.1.22/ext/phar/tests/bug81726.gz - a hacktool program Tool.Zipbomb.3
I believe that the archive isn't needed in final php images.

[yosifkit]

Duplicate of #488. The PHP source is kept so that users can install extensions that are not included by default (like via the docker-php-ext-* scripts).

Related issue: #1394