importccl: fix test for duplicate collated string primary keys

Previously the test for duplicate collated string primary keys had an
incorrectly formed CSV as the test data. This change fixes the test data by
adding the collation to all of the rows in the CSV.

Release note: None

pkg/ccl/importccl/import_stmt_test.go

@@ -168,14 +168,13 @@ ORDER BY table_name
 				s string collate en_u_ks_level1 primary key
 			`,
 			typ: "CSV",
-			data: `a
-B
-c
-D
-d
+			data: `'a' collate en_u_ks_level1
+'B' collate en_u_ks_level1
+'c' collate en_u_ks_level1
+'D' collate en_u_ks_level1
+'d' collate en_u_ks_level1
 `,
-			err:       "duplicate key",
-			skipIssue: 53956,
+			err: "duplicate key",
 		},
 		{
 			name: "duplicate PK at sst boundary",