MDEV-30946 Index usage for DATE(datetime_column) = const does not work for DELETE and UPDATE

Add date conditions transformation to the execution paths
of DELETE and UPDATE commands.

Strip excessive prepared statements from the test file

sql/sql_delete.cc

@@ -464,6 +464,12 @@ bool Sql_cmd_delete::delete_from_single_table(THD *thd)
         goto produce_explain_and_leave;
     }
   }
+  if (conds && thd->lex->are_date_funcs_used())
+  {
+    /* Rewrite datetime comparison conditions into sargable */
+    conds= conds->top_level_transform(thd, &Item::date_conds_transformer,
+                                      (uchar *) 0);
+  }
 
 #ifdef WITH_PARTITION_STORAGE_ENGINE
   if (prune_partitions(thd, table, conds))

sql/sql_update.cc

@@ -433,6 +433,12 @@ bool Sql_cmd_update::update_single_table(THD *thd)
         goto produce_explain_and_leave;
     }
   }
+  if (conds && thd->lex->are_date_funcs_used())
+  {
+    /* Rewrite datetime comparison conditions into sargable */
+    conds= conds->top_level_transform(thd, &Item::date_conds_transformer,
+                                      (uchar *) 0);
+  }
 
   // Don't count on usage of 'only index' when calculating which key to use
   table->covering_keys.clear_all();