ccl/sqlproxyccl: deflake TestConnectionMigration

Fixes cockroachdb#106885.

This test flake seems extremely rare, and it's unclear why it occurred in the
first place. The past 1000 runs (all of what TC has) have been successful.
Regardless, this commit attempts at deflaking TestConnectionMigration. Given
that some subtests transfer connections through `transferConnWithRetries`, it
is possible that the transfer was retried, causing the metric to be
incremented.

Release note: None

Epic: none

Author: jaylim-crl

pkg/ccl/sqlproxyccl/proxy_handler_test.go

@@ -2066,6 +2066,7 @@ func TestConnectionMigration(t *testing.T) {
 
 			// Now attempt a transfer concurrently with requests.
 			initSuccessCount := f.metrics.ConnMigrationSuccessCount.Count()
+			initErrorRecoverableCount := f.metrics.ConnMigrationErrorRecoverableCount.Count()
 			subCtx, cancel := context.WithCancel(tCtx)
 			defer cancel()
 
@@ -2105,7 +2106,7 @@ func TestConnectionMigration(t *testing.T) {
 
 			// Check metrics.
 			require.True(t, f.metrics.ConnMigrationSuccessCount.Count() > initSuccessCount+4)
-			require.Equal(t, int64(0), f.metrics.ConnMigrationErrorRecoverableCount.Count())
+			require.Equal(t, initErrorRecoverableCount, f.metrics.ConnMigrationErrorRecoverableCount.Count())
 			require.Equal(t, int64(0), f.metrics.ConnMigrationErrorFatalCount.Count())
 
 			validateMiscMetrics(t)
@@ -2115,6 +2116,7 @@ func TestConnectionMigration(t *testing.T) {
 		// transfers should not close the connection.
 		t.Run("failed_transfers_with_tx", func(t *testing.T) {
 			initSuccessCount := f.metrics.ConnMigrationSuccessCount.Count()
+			initErrorRecoverableCount := f.metrics.ConnMigrationErrorRecoverableCount.Count()
 			initAddr := queryAddr(tCtx, t, db)
 
 			err = crdb.ExecuteTx(tCtx, db, nil /* txopts */, func(tx *gosql.Tx) error {
@@ -2149,15 +2151,16 @@ func TestConnectionMigration(t *testing.T) {
 			// still be active.
 			require.Nil(t, f.ctx.Err())
 			require.Equal(t, initSuccessCount, f.metrics.ConnMigrationSuccessCount.Count())
-			require.Equal(t, int64(5), f.metrics.ConnMigrationErrorRecoverableCount.Count())
+			require.Equal(t, initErrorRecoverableCount+5,
+				f.metrics.ConnMigrationErrorRecoverableCount.Count())
 			require.Equal(t, int64(0), f.metrics.ConnMigrationErrorFatalCount.Count())
 
 			// Once the transaction is closed, transfers should work.
 			require.NoError(t, transferConnWithRetries(t, f))
 			require.NotEqual(t, initAddr, queryAddr(tCtx, t, db))
 			require.Nil(t, f.ctx.Err())
 			require.Equal(t, initSuccessCount+1, f.metrics.ConnMigrationSuccessCount.Count())
-			require.Equal(t, int64(5), f.metrics.ConnMigrationErrorRecoverableCount.Count())
+			require.True(t, f.metrics.ConnMigrationErrorRecoverableCount.Count() >= initErrorRecoverableCount+5)
 			require.Equal(t, int64(0), f.metrics.ConnMigrationErrorFatalCount.Count())
 
 			validateMiscMetrics(t)