feat(prover): cleanup more database related code

prover/guardian_prover_heartbeater/guardian_prover.go

@@ -226,11 +226,6 @@ func (s *GuardianProverHeartBeater) signBlock(ctx context.Context, blockID *big.
 	return signed, header, nil
 }
 
-// Close closes the underlying database.
-func (s *GuardianProverHeartBeater) Close() error {
-	return nil
-}
-
 // SendHeartbeat sends a heartbeat to the health check server.
 func (s *GuardianProverHeartBeater) SendHeartbeat(
 	ctx context.Context,

prover/guardian_prover_heartbeater/interface.go

@@ -27,5 +27,4 @@ type Heartbeater interface {
 type BlockSenderHeartbeater interface {
 	BlockSigner
 	Heartbeater
-	Close() error
 }

prover/prover.go

@@ -321,12 +321,6 @@ func (p *Prover) eventLoop() {
 
 // Close closes the prover instance.
 func (p *Prover) Close(ctx context.Context) {
-	if p.guardianProverHeartbeater != nil {
-		if err := p.guardianProverHeartbeater.Close(); err != nil {
-			log.Error("failed to close database connection", "error", err)
-		}
-	}
-
 	if err := p.server.Shutdown(ctx); err != nil {
 		log.Error("Failed to shut down prover server", "error", err)
 	}