Sync: Fire accountRemoved KV store reason when no account (#1189)

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**Required**:

Task/Issue URL:
https://app.asana.com/0/1202926619870900/1209014391063056/f
iOS PR: duckduckgo/iOS#3875
macOS PR: duckduckgo/macos-browser#3782
What kind of version bump will this require?: Minor

**Description**:

As part of [✓ Send pixels for account removal + decoding
issues](https://app.asana.com/0/1199230911884351/1208723035104886/f),
pixels were added indicating what the reason for the Sync account being
removed from the Keychain was.

However, the pixel
`sync_account_removed_reason_not-set-on-key-value-store` is being sent
even when there was no account stored in the keychain in the first
place. This could be obscuring a problem.

To make this Pixel more useful, we should update it so that it's only
sent when there was an account stored in the keychain.

**Steps to test this PR**:
Hard to test the pixel itself as reporting on a broken state, but just
do a quick smoke test of Sync on both platforms.

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**OS Testing**:

* [ ] iOS 14
* [ ] iOS 15
* [ ] iOS 16
* [ ] macOS 10.15
* [ ] macOS 11
* [ ] macOS 12

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###### Internal references:
[Software Engineering
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[Technical Design
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Sources/DDGSync/DDGSync.swift

@@ -226,8 +226,10 @@ public class DDGSync: DDGSyncing {
 
         let syncEnabled = dependencies.keyValueStore.object(forKey: Constants.syncEnabledKey) != nil
         guard syncEnabled else {
+            if account != nil {
+                dependencies.errorEvents.fire(.accountRemoved(.syncEnabledNotSetOnKeyValueStore))
+            }
             try? dependencies.secureStore.removeAccount()
-            dependencies.errorEvents.fire(.accountRemoved(.syncEnabledNotSetOnKeyValueStore))
             authState = .inactive
             return
         }