services/horizon: Update cursor when bumping ledger to latest (#4150)

Update cursor in Stellar-Core to latest ingested ledger when local ingestion is
behind the cluster.

If there is a DB ingesting instance more than one ingesting instance: either
Captive-Core or DB connected to another Stellar-Core, it's possible that the
cursor will be updated very rarely. This will make the Stellar-Core DB size
bloat as the old ledger will not be removed.

services/horizon/internal/ingest/fsm.go

@@ -416,6 +416,14 @@ func (r resumeState) run(s *system) (transition, error) {
 		log.WithField("ingestLedger", ingestLedger).
 			WithField("lastIngestedLedger", lastIngestedLedger).
 			Info("bumping ingest ledger to next ledger after ingested ledger in db")
+
+		// Update cursor if there's more than one ingesting instance: either
+		// Captive-Core or DB ingestion connected to another Stellar-Core.
+		if err = s.updateCursor(lastIngestedLedger); err != nil {
+			// Don't return updateCursor error.
+			log.WithError(err).Warn("error updating stellar-core cursor")
+		}
+
 		return retryResume(resumeState{
 			latestSuccessfullyProcessedLedger: lastIngestedLedger,
 		}), nil

services/horizon/internal/ingest/resume_state_test.go

@@ -304,6 +304,13 @@ func (s *ResumeTestTestSuite) TestBumpIngestLedger() {
 	s.historyQ.On("Begin").Return(nil).Once()
 	s.historyQ.On("GetLastLedgerIngest", s.ctx).Return(uint32(101), nil).Once()
 
+	s.stellarCoreClient.On(
+		"SetCursor",
+		mock.AnythingOfType("*context.timerCtx"),
+		defaultCoreCursorName,
+		int32(101),
+	).Return(errors.New("my error")).Once()
+
 	next, err := resumeState{latestSuccessfullyProcessedLedger: 99}.run(s.system)
 	s.Assert().NoError(err)
 	s.Assert().Equal(