Coding Standards: Clarify time units for various timeout or expiration values.

This changeset implements a clearer and more consistent timeout/duration/expiration format. It updates time durations used in various files, as per WordPress coding standards:

- If the value can be represented as an integer (not a fractional) number of minutes (hours, etc.), use the appropriate constant (e.g.: `MINUTE_IN_SECONDS`) multiplied by that number.
- Otherwise, keep the value as is and add a comment with the units for clarity.

Follow-up to [11823], [13177], [21996], [37747], [53714].

Props hztyfoon, audrasjb, arrasel403, krupalpanchal, GaryJ, SergeyBiryukov, peterwilsoncc, rudlinkon, costdev, robinwpdeveloper.
Fixes #56293.
See #55647.


git-svn-id: https://develop.svn.wordpress.org/trunk@54113 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/options.php

@@ -345,7 +345,7 @@ if ( 'update' === $action ) { // We are saving settings sent from a settings pag
 		add_settings_error( 'general', 'settings_updated', __( 'Settings saved.' ), 'success' );
 	}
 
-	set_transient( 'settings_errors', get_settings_errors(), MINUTE_IN_SECONDS / 2 );
+	set_transient( 'settings_errors', get_settings_errors(), 30 ); // 30 seconds.
 
 	// Redirect back to the settings page that was submitted.
 	$goback = add_query_arg( 'settings-updated', 'true', wp_get_referer() );