Filter/Filter: remove outdated code that is no longer needed

This commit removes an if condition to maintain backwards compatibility
that is no longer needed. It was added via squizlabs/PHP_CodeSniffer@4982619
to preserve backwards compatibility back in a time when it was possible
to programmatically set ignore patterns using
`CodeSniffer::setIgnorePatterns()` (see https://pear.php.net/bugs/bug.php?id=19859).
This method was removed a long time ago via f61025c#diff-c36ecedca179eab0b3cd245e872a96ab26fa08e567437e167f4eda1779c15c89L431-L435,
and since then, there is no way for users to set the ignore pattern
array with numeric indices.

Author: rodrigoprimo

src/Filters/Filter.php

@@ -247,13 +247,6 @@ protected function shouldIgnorePath($path)
         }
 
         foreach ($ignorePatterns as $pattern => $type) {
-            // Maintains backwards compatibility in case the ignore pattern does
-            // not have a relative/absolute value.
-            if (is_int($pattern) === true) {
-                $pattern = $type;
-                $type    = 'absolute';
-            }
-
             $replacements = [
                 '\\,' => ',',
                 '*'   => '.*',