flaky test for disttask resource control

[lance6716]

https://do.pingcap.net/jenkins/blue/organizations/jenkins/pingcap%2Ftidb%2Fghpr_check2/detail/ghpr_check2/9921/

    testkit.go:273: 
        	Error Trace:	pkg/testkit/testkit.go:273
        	            				pkg/testkit/testkit.go:198
        	            				pkg/testkit/testkit.go:173
        	            				tests/realtikvtest/importintotest/import_into_test.go:336
        	Error:      	Received unexpected error:
        	            	task concurrency(26) larger than cpu count(16) of managed node
        	            	github.com/pingcap/tidb/pkg/disttask/framework/storage.(*TaskManager).CreateTaskWithSession
        	            		pkg/disttask/framework/storage/task_table.go:219
        	            	github.com/pingcap/tidb/pkg/disttask/framework/planner.(*Planner).Run
        	            		pkg/disttask/framework/planner/planner.go:42
        	            	github.com/pingcap/tidb/pkg/disttask/importinto.doSubmitTask.func1
        	            		pkg/disttask/importinto/job.go:94
        	            	github.com/pingcap/tidb/pkg/disttask/framework/storage.(*TaskManager).WithNewTxn.func1
        	            		pkg/disttask/framework/storage/task_table.go:171
        	            	github.com/pingcap/tidb/pkg/disttask/framework/storage.(*TaskManager).WithNewSession
        	            		pkg/disttask/framework/storage/task_table.go:147
        	            	github.com/pingcap/tidb/pkg/disttask/framework/storage.(*TaskManager).WithNewTxn
        	            		pkg/disttask/framework/storage/task_table.go:153
        	            	github.com/pingcap/tidb/pkg/disttask/importinto.doSubmitTask
        	            		pkg/disttask/importinto/job.go:68
        	            	github.com/pingcap/tidb/pkg/disttask/importinto.SubmitTask
        	            		pkg/disttask/importinto/job.go:52
        	            	github.com/pingcap/tidb/pkg/executor.(*ImportIntoExec).submitTask
        	            		pkg/executor/import_into.go:185
        	            	github.com/pingcap/tidb/pkg/executor.(*ImportIntoExec).Next
        	            		pkg/executor/import_into.go:134
        	            	github.com/pingcap/tidb/pkg/executor/internal/exec.Next
        	            		pkg/executor/internal/exec/executor.go:410
        	            	github.com/pingcap/tidb/pkg/executor.(*ExecStmt).next
        	            		pkg/executor/adapter.go:1211
        	            	github.com/pingcap/tidb/pkg/executor.(*recordSet).Next
        	            		pkg/executor/adapter.go:160
        	            	github.com/pingcap/tidb/pkg/session.GetRows4Test
        	            		pkg/session/tidb.go:346
        	            	github.com/pingcap/tidb/pkg/session.ResultSetToStringSlice
        	            		pkg/session/tidb.go:364
        	            	github.com/pingcap/tidb/pkg/testkit.(*TestKit).ResultSetToResultWithCtx
        	            		pkg/testkit/testkit.go:272
        	            	github.com/pingcap/tidb/pkg/testkit.(*TestKit).MustQueryWithContext
        	            		pkg/testkit/testkit.go:198
        	            	github.com/pingcap/tidb/pkg/testkit.(*TestKit).MustQuery
        	            		pkg/testkit/testkit.go:173
        	            	tests/realtikvtest/importintotest/importintotest_test.(*mockGCSSuite).TestGeneratedColumnsAndTSVFile
        	            		tests/realtikvtest/importintotest/import_into_test.go:336
        	            	reflect.Value.call
        	            		GOROOT/src/reflect/value.go:596
        	            	reflect.Value.Call
        	            		GOROOT/src/reflect/value.go:380
        	            	github.com/stretchr/testify/suite.Run.func1
        	            		external/com_github_stretchr_testify/suite/suite.go:202
        	            	testing.tRunner
        	            		GOROOT/src/testing/testing.go:1595
        	            	runtime.goexit
        	            		src/runtime/asm_amd64.s:1650
        	Test:       	TestImportInto
        	Messages:   	sql:IMPORT INTO load_csv.t_gen2(b)
        	            			FROM 'gcs://test-bucket/generated_columns.csv?endpoint=http://127.0.0.1:4443/storage/v1/' WITH fields_terminated_by='\t', args:[]
=== NAME  TestImportInto/TestGeneratedColumnsAndTSVFile

    import_into_test.go:546: 
        	Error Trace:	tests/realtikvtest/importintotest/import_into_test.go:546
        	Error:      	Error "task concurrency(26) larger than cpu count(16) of managed node" does not contain "Incorrect string value '\\xF0\\x9F\\x98\\x80' for column 'j'"
        	Test:       	TestImportInto/TestGBK