Tests: Replace confusing assertLessThan with explicit comparisons in admin menu order test

[Copilot]

PHPUnit's assertLessThan($expected, $actual) signature is counterintuitive — the first argument is the upper bound, not the value being tested as "less than" — making it easy to misread the assertions as testing the opposite order.

Change

Replaced assertLessThan calls with assertTrue + explicit inequality expressions, making the comparison direction immediately obvious:

// Before — confusing: which arg is "less than"?
$this->assertLessThan( $backup_submenu_position, $videopress_submenu_position, '...' );

// After — unambiguous
$this->assertTrue( $videopress_submenu_position < $backup_submenu_position, '...' );

Applies to all four ordering assertions: VideoPress → Backup → Search → Settings → Activity Log. Test semantics are unchanged.

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