Remove tests for unserializing old (^2.14) parser results

I think it is not important so support unserializing parser results from another major version release.

The tests made sense when they were added in a bugfix release back in #10684, but not anymore for the 4.0.x branch.

Author: mpdude

tests/Tests/ORM/Functional/ParserResultSerializationTest.php

@@ -68,22 +68,6 @@ static function (ParserResult $parserResult): ParserResult {
         ];
     }
 
-    #[DataProvider('provideSerializedSingleSelectResults')]
-    public function testUnserializeSingleSelectResult(string $serialized): void
-    {
-        $unserialized = unserialize($serialized);
-
-        $this->assertInstanceOf(ParserResult::class, $unserialized);
-        $this->assertInstanceOf(ResultSetMapping::class, $unserialized->getResultSetMapping());
-        $this->assertEquals(['name' => [0]], $unserialized->getParameterMappings());
-    }
-
-    /** @return Generator<string, array{string}> */
-    public static function provideSerializedSingleSelectResults(): Generator
-    {
-        yield '2.17.0' => [rtrim(file_get_contents(__DIR__ . '/ParserResults/single_select_2_17_0.txt'), "\n")];
-    }
-
     public function testSymfony44ProvidedData(): void
     {
         $sqlExecutor      = new FinalizedSelectExecutor('test');