Code Modernization: Remove error suppression from `parse_url()` calls.

Previously, the `@` operator was used to prevent possible warnings emitted by `parse_url()` in PHP < 5.3.3 when URL parsing failed.

Now that the minimum version of PHP required by WordPress is 5.6.20, this is no longer needed.

Props netpassprodsr, Howdy_McGee.
Fixes #49980. See #24780.
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git-svn-id: https://core.svn.wordpress.org/trunk@47392 1a063a9b-81f0-0310-95a4-ce76da25c4cd