Refactor getPartitionMethod()

Signed-off-by: Kamil Tekiela <tekiela246@gmail.com>

phpstan-baseline.neon

@@ -11118,12 +11118,6 @@ parameters:
 			count: 2
 			path: src/Partitioning/Partition.php
 
-		-
-			message: '#^Method PhpMyAdmin\\Partitioning\\Partition\:\:getPartitionMethod\(\) should return string\|null but returns mixed\.$#'
-			identifier: return.type
-			count: 1
-			path: src/Partitioning/Partition.php
-
 		-
 			message: '#^Only booleans are allowed in an if condition, string\|false\|null given\.$#'
 			identifier: if.condNotBoolean

psalm-baseline.xml

@@ -6497,12 +6497,6 @@
       <code><![CDATA[$this->name]]></code>
       <code><![CDATA[$value]]></code>
     </MixedAssignment>
-    <MixedInferredReturnType>
-      <code><![CDATA[string|null]]></code>
-    </MixedInferredReturnType>
-    <MixedReturnStatement>
-      <code><![CDATA[$partitionMethod[0]]]></code>
-    </MixedReturnStatement>
     <PossiblyInvalidArgument>
       <code><![CDATA[$row]]></code>
     </PossiblyInvalidArgument>

src/Partitioning/Partition.php

@@ -207,14 +207,14 @@ class Partition extends SubPartition
     {
         if (self::havePartitioning()) {
             $dbi = DatabaseInterface::getInstance();
-            $partitionMethod = $dbi->fetchResultSimple(
+            $partitionMethod = $dbi->fetchValue(
                 'SELECT `PARTITION_METHOD` FROM `information_schema`.`PARTITIONS`'
                 . ' WHERE `TABLE_SCHEMA` = ' . $dbi->quoteString($db)
                 . ' AND `TABLE_NAME` = ' . $dbi->quoteString($table)
                 . ' LIMIT 1',
             );
-            if ($partitionMethod !== []) {
-                return $partitionMethod[0];
+            if ($partitionMethod !== false) {
+                return $partitionMethod;
             }
         }