chore(metrics): Remove custom array lookup (#77234)

Removes custom array lookup created for custom lookups related to span
attribute metrics.

This is no longer used anywhere and there is no need to keep it in a
codebase.

Signed-off-by: Vjeran Grozdanic <[email protected]>

Author: vgrozdanic

src/sentry/db/models/fields/array.py

@@ -2,11 +2,9 @@
 
 import ast
 
-from django.contrib.postgres.fields import ArrayField as DjangoArrayField
 from django.db import models
 
 from sentry.db.models.utils import Creator
-from sentry.db.postgres.lookups.array_element_contains import ArrayElementContainsLookup
 from sentry.utils import json
 
 
@@ -71,6 +69,3 @@ def to_python(self, value):
                     assert "\\" not in value, "Unexpected ArrayField format"
                     value = value[1:-1].split(",")
         return [self.of.to_python(x) for x in value]
-
-
-DjangoArrayField.register_lookup(ArrayElementContainsLookup)