DEV: Fix flaky test due to ActiveRecord query caching (#24476)

Why this change?

The test was randomly failing in
https://github.com/discourse/discourse/actions/runs/6936264158/job/18868087113
with the following failure:

```
expect do user.update_ip_address!("127.0.0.1") end.to change {
  UserIpAddressHistory.where(user_id: user.id).count
}.by(1)

expected `UserIpAddressHistory.where(user_id: user.id).count` to have changed by 1, but was changed by 0
```

This is due to the fact that ActiveRecord will actually cache the result
of `UserIpAddressHistory.where(user_id: user.id).count`. However,
`User.update_ip_address!` relies on mini_sql and does not go through
ActiveRecord. As a result, the query cache is not cleared and hence the
flakiness.

What does this change do?

This change uses the `uncached` method provided by ActiveRecord when
we are fetching the count.

spec/models/user_spec.rb

@@ -3048,19 +3048,19 @@ RSpec.describe User do
 
       it "tracks old user record correctly" do
         expect do user.update_ip_address!("127.0.0.1") end.to change {
-          UserIpAddressHistory.where(user_id: user.id).count
+          UserIpAddressHistory.uncached { UserIpAddressHistory.where(user_id: user.id).count }
         }.by(1)
 
         freeze_time 10.minutes.from_now
 
         expect do user.update_ip_address!("0.0.0.0") end.to change {
-          UserIpAddressHistory.where(user_id: user.id).count
+          UserIpAddressHistory.uncached { UserIpAddressHistory.where(user_id: user.id).count }
         }.by(1)
 
         freeze_time 11.minutes.from_now
 
         expect do user.update_ip_address!("127.0.0.1") end.to_not change {
-          UserIpAddressHistory.where(user_id: user.id).count
+          UserIpAddressHistory.uncached { UserIpAddressHistory.where(user_id: user.id).count }
         }
 
         expect(
@@ -3070,7 +3070,7 @@ RSpec.describe User do
         freeze_time 12.minutes.from_now
 
         expect do user.update_ip_address!("0.0.0.1") end.not_to change {
-          UserIpAddressHistory.where(user_id: user.id).count
+          UserIpAddressHistory.uncached { UserIpAddressHistory.where(user_id: user.id).count }
         }
 
         expect(UserIpAddressHistory.where(user_id: user.id).pluck(:ip_address).map(&:to_s)).to eq(