kvcoord: add logging in TestWaiterOnRejectedCommit

This should help debugging/deflaking this test should it fail again. The
conjecture is that we end up with more than one command ID, and only one
gets the injected error, while another one succeeds.

Epic: none
Release note: none

Author: pav-kv

pkg/kv/kvclient/kvcoord/integration_test.go

@@ -85,6 +85,7 @@ func TestWaiterOnRejectedCommit(t *testing.T) {
 					if !ba.Txn.ID.Equal(v.(uuid.UUID)) {
 						return nil
 					}
+					t.Logf("EndTxn command ID: %v", args.CmdID)
 					commitCmdID.Store(args.CmdID)
 					return nil
 				},
@@ -99,10 +100,12 @@ func TestWaiterOnRejectedCommit(t *testing.T) {
 					if args.CmdID == cmdID {
 						if illegalLeaseIndex {
 							illegalLeaseIndex = false
-							// NB: 1 is proposalIllegalLeaseIndex.
+							t.Logf("injecting illegal lease index for %v", cmdID)
+							// NB: 1 is ProposalRejectionIllegalLeaseIndex.
 							return 1, kvpb.NewErrorf("test injected err (illegal lease index)")
 						}
-						// NB: 0 is proposalNoReevaluation.
+						t.Logf("injecting permanent rejection for %v", cmdID)
+						// NB: 0 is ProposalRejectionPermanent.
 						return 0, kvpb.NewErrorf("test injected err")
 					}
 					return 0, nil
@@ -162,6 +165,7 @@ func TestWaiterOnRejectedCommit(t *testing.T) {
 			t.Fatal(err)
 		}
 	}
+	t.Logf("txn ID: %v", txn.ID())
 	txnID.Store(txn.ID())
 
 	readerDone := make(chan error, 2)