Move rate limiter reset to defer block (#4722)

Move `ResetLimiter()` call to defer block to ensure that it gets called even if the backup fails. Without this change, any following mailbox backups may get artificially throttled by limiter.

---

#### Does this PR need a docs update or release note?

- [ ] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [x] ⛔ No

#### Type of change

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- [ ] 🌻 Feature
- [x] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

#### Issue(s)

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* #<issue>

#### Test Plan

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- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

src/internal/operations/backup.go

@@ -210,6 +210,12 @@ func (op *BackupOperation) Run(ctx context.Context) (err error) {
 	// Select an appropriate rate limiter for the service.
 	ctx = op.bp.SetRateLimiter(ctx, op.Selectors.PathService(), op.Options)
 
+	// For exchange, rate limits are enforced on a mailbox level. Reset the
+	// rate limiter so that it doesn't accidentally throttle following mailboxes.
+	// This is a no-op if we are using token bucket limiter since it refreshes
+	// tokens on a fixed per second basis.
+	defer graph.ResetLimiter(ctx)
+
 	// Check if the protected resource has the service enabled in order for us
 	// to run a backup.
 	enabled, err := op.bp.IsServiceEnabled(
@@ -328,12 +334,6 @@ func (op *BackupOperation) Run(ctx context.Context) (err error) {
 		logger.Ctx(ctx).Infow("completed backup", "results", op.Results)
 	}
 
-	// For exchange, rate limits are enforced on a mailbox level. Reset the
-	// rate limiter so that it doesn't accidentally throttle following mailboxes.
-	// This is a no-op if we are using token bucket limiter since it refreshes
-	// tokens on a fixed per second basis.
-	graph.ResetLimiter(ctx)
-
 	return op.Errors.Failure()
 }