MDEV-31936 Simplify deinit_spider.inc

Spider is part of the server, and there's no need to check the
version.

All spider plugins are uninstalled in clean_up_spider.inc

DROP SERVER IF EXISTS makes things easier

storage/spider/mysql-test/spider/include/deinit_spider.inc

-let $SERVER_NAME=
-  `SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(version(), '-', 2), '-', -1)`;
-let $SERVER_MAJOR_VERSION=
-  `SELECT SUBSTRING_INDEX(version(), '.', 1)`;
-let $SERVER_MINOR_VERSION=
-  `SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(version(), '.', 2), '.', -1)`;
-let $PLUGIN_VERSION=
-  `SELECT SUBSTRING_INDEX(plugin_version, '.', 1)
-     FROM information_schema.plugins
-    WHERE plugin_name = 'SPIDER'`;
-if (`SELECT IF($PLUGIN_VERSION = 3, 1, 0)`)
-{
-  let $HAS_REWRITE=
-    `SELECT IF (STRCMP('$SERVER_NAME', 'MariaDB') = 0,
-                IF ($SERVER_MAJOR_VERSION = 10,
-                    IF ($SERVER_MINOR_VERSION < 4,  0, 1),
-                    IF ($SERVER_MAJOR_VERSION < 10, 0, 1)),
-                0)`;
-  let $HAS_REWRITE= 0;
-  if ($HAS_REWRITE)
-  {
-    DROP FUNCTION spider_flush_rewrite_cache;
-    UNINSTALL PLUGIN spider_rewrite;
-    DROP TABLE IF EXISTS mysql.spider_rewrite_tables;
-    DROP TABLE IF EXISTS mysql.spider_rewrite_table_tables;
-    DROP TABLE IF EXISTS mysql.spider_rewrite_table_partitions;
-    DROP TABLE IF EXISTS mysql.spider_rewrite_table_subpartitions;
-    DROP TABLE IF EXISTS mysql.spider_rewritten_tables;
-  }
-}
 --source clean_up_spider.inc
-if ($VERSION_COMPILE_OS_WIN)
-{
-  if ($CHILD2_1_MYPORT)
-  {
-    DROP SERVER s_2_1;
-  }
-  if ($CHILD2_2_MYPORT)
-  {
-    DROP SERVER s_2_2;
-  }
-  if ($CHILD2_3_MYPORT)
-  {
-    DROP SERVER s_2_3;
-  }
-  if ($CHILD3_1_MYPORT)
-  {
-    DROP SERVER s_3_1;
-  }
-  if ($CHILD3_2_MYPORT)
-  {
-    DROP SERVER s_3_2;
-  }
-  if ($CHILD2_3_MYPORT)
-  {
-    DROP SERVER s_3_3;
-  }
-}
-if (!$VERSION_COMPILE_OS_WIN)
-{
-  if ($CHILD2_1_MYSOCK)
-  {
-    DROP SERVER s_2_1;
-  }
-  if ($CHILD2_2_MYSOCK)
-  {
-    DROP SERVER s_2_2;
-  }
-  if ($CHILD2_3_MYSOCK)
-  {
-    DROP SERVER s_2_3;
-  }
-  if ($CHILD3_1_MYSOCK)
-  {
-    DROP SERVER s_3_1;
-  }
-  if ($CHILD3_2_MYSOCK)
-  {
-    DROP SERVER s_3_2;
-  }
-  if ($CHILD3_3_MYSOCK)
-  {
-    DROP SERVER s_3_3;
-  }
-}
+DROP SERVER IF EXISTS s_2_1;
+DROP SERVER IF EXISTS s_2_2;
+DROP SERVER IF EXISTS s_2_3;
+DROP SERVER IF EXISTS s_3_1;
+DROP SERVER IF EXISTS s_3_2;
+DROP SERVER IF EXISTS s_3_3;