Remove renaming index

This was causing problems when the index already had the new, correct, name.
We should just give it a name ourselves and write some sql that cleans up both

See #1680

wger/nutrition/migrations/0020_full_text_search.py

@@ -14,7 +14,8 @@ class Migration(migrations.Migration):
         migrations.AddIndex(
             model_name='ingredient',
             index=django.contrib.postgres.indexes.GinIndex(
-                fields=['name'], name='nutrition_i_search__f274b7_gin'
+                fields=['name'],
+                name='nutrition_i_search__f274b7_gin'
             ),
         ),
     ]

wger/nutrition/migrations/0021_add_fibers_field.py

@@ -9,11 +9,6 @@ class Migration(migrations.Migration):
     ]
 
     operations = [
-        migrations.RenameIndex(
-            model_name='ingredient',
-            new_name='nutrition_i_name_8f538f_gin',
-            old_name='nutrition_i_search__f274b7_gin',
-        ),
         migrations.AddField(
             model_name='nutritionplan',
             name='goal_fibers',