drt: fix potential db conn leaks

Close `rows` from `conn.QueryContext` added
in [1] and [2].

[1] #144365
[2] #144367

Epic: none
Release note: None

Author: srosenberg

pkg/cmd/roachtest/operations/cancel_job.go

@@ -35,6 +35,8 @@ func runCancelJob(
 			o.Fatal(err)
 		}
 
+		defer rows.Close()
+
 		var jobIds []string
 		for rows.Next() {
 			var jobId string

pkg/cmd/roachtest/operations/pause_job.go

@@ -54,6 +54,8 @@ func runPauseJob(
 			o.Fatal(err)
 		}
 
+		defer rows.Close()
+
 		var jobIds []string
 		for rows.Next() {
 			var jobId string

pkg/cmd/roachtest/roachtestutil/operations/dependency.go

@@ -81,6 +81,8 @@ func checkPopulatedDatabase(
 	if err != nil {
 		return false, err
 	}
+	defer dbsCount.Close()
+
 	dbsCount.Next()
 	var count int
 	if err := dbsCount.Scan(&count); err != nil {
@@ -99,6 +101,8 @@ func checkZeroUnavailableRanges(
 	if err != nil {
 		return false, err
 	}
+	defer rangesCur.Close()
+
 	rangesCur.Next()
 	var count int
 	if err := rangesCur.Scan(&count); err != nil {
@@ -117,6 +121,8 @@ func checkZeroUnderreplicatedRanges(
 	if err != nil {
 		return false, err
 	}
+	defer rangesCur.Close()
+
 	rangesCur.Next()
 	var count int
 	if err := rangesCur.Scan(&count); err != nil {
@@ -135,6 +141,8 @@ func checkLDRJobRunning(
 	if err != nil {
 		return false, err
 	}
+	defer jobsCur.Close()
+
 	jobsCur.Next()
 	var jobId string
 	_ = jobsCur.Scan(&jobId)
@@ -152,6 +160,8 @@ func checkBackupJobRunning(
 	if err != nil {
 		return false, err
 	}
+	defer jobsCur.Close()
+
 	jobsCur.Next()
 	var jobId string
 	_ = jobsCur.Scan(&jobId)
@@ -169,6 +179,8 @@ func checkRestoreJobRunning(
 	if err != nil {
 		return false, err
 	}
+	defer jobsCur.Close()
+
 	jobsCur.Next()
 	var jobId string
 	_ = jobsCur.Scan(&jobId)