Take less memory if their fields were sorted

1. What did you do?

golangci-lint run --disable-all -E maligned

2. What did you expect to see?

• No output

3. What did you see instead?

types/json/binary_test.go:159:16: struct of size 80 bytes could be of size 72 bytes (maligned)
	var tests = []struct {
	              ^
sessionctx/stmtctx/stmtctx.go:49:23: struct of size 552 bytes could be of size 528 bytes (maligned)
type StatementContext struct {
                      ^
sessionctx/stmtctx/stmtctx.go:148:16: struct of size 24 bytes could be of size 16 bytes (maligned)
type StmtHints struct {
               ^
config/config.go:58:13: struct of size 1048 bytes could be of size 1016 bytes (maligned)
type Config struct {
            ^
store/tikv/tikvrpc/tikvrpc.go:143:14: struct of size 152 bytes could be of size 144 bytes (maligned)
type Request struct {
             ^
types/convert_test.go:888:13: struct of size 56 bytes could be of size 48 bytes (maligned)
	tests := []struct {
	           ^
sessionctx/variable/session.go:194:18: struct of size 1032 bytes could be of size 952 bytes (maligned)
type SessionVars struct {
                 ^
table/index.go:33:19: struct of size 32 bytes could be of size 24 bytes (maligned)
type CreateIdxOpt struct {
                  ^
planner/util/path.go:27:17: struct of size 272 bytes could be of size 264 bytes (maligned)
type AccessPath struct {
                ^
store/tikv/2pc.go:102:24: struct of size 240 bytes could be of size 232 bytes (maligned)
type twoPhaseCommitter struct {
                       ^
store/tikv/client_batch.go:38:16: struct of size 96 bytes could be of size 88 bytes (maligned)
type batchConn struct {
               ^
store/tikv/kv.go:130:16: struct of size 240 bytes could be of size 232 bytes (maligned)
type tikvStore struct {
               ^
planner/memo/group.go:76:12: struct of size 80 bytes could be of size 72 bytes (maligned)
type Group struct {
           ^
expression/builtin.go:43:22: struct of size 104 bytes could be of size 88 bytes (maligned)
type baseBuiltinFunc struct {
                     ^
expression/builtin_cast_test.go:833:24: struct of size 56 bytes could be of size 48 bytes (maligned)
	castToTimeCases2 := []struct {
	                      ^
planner/core/common_plans.go:521:13: struct of size 368 bytes could be of size 360 bytes (maligned)
type Insert struct {
            ^
planner/core/physical_plans.go:364:29: struct of size 528 bytes could be of size 520 bytes (maligned)
type PhysicalIndexMergeJoin struct {
                            ^
executor/distsql.go:202:26: struct of size 392 bytes could be of size 376 bytes (maligned)
type IndexReaderExecutor struct {
                         ^
executor/distsql.go:317:26: struct of size 472 bytes could be of size 432 bytes (maligned)
type IndexLookUpExecutor struct {
                         ^
executor/insert_common.go:35:19: struct of size 384 bytes could be of size 368 bytes (maligned)
type InsertValues struct {
                  ^
executor/join.go:42:19: struct of size 448 bytes could be of size 432 bytes (maligned)
type HashJoinExec struct {
                  ^
executor/join.go:719:26: struct of size 392 bytes could be of size 384 bytes (maligned)
type NestedLoopApplyExec struct {
                         ^
executor/load_data.go:498:18: struct of size 88 bytes could be of size 80 bytes (maligned)
type fieldWriter struct {
                 ^
executor/update.go:33:17: struct of size 272 bytes could be of size 264 bytes (maligned)
type UpdateExec struct {
                ^
executor/benchmark_test.go:532:23: struct of size 104 bytes could be of size 96 bytes (maligned)
type hashJoinTestCase struct {
                      ^
types/time_test.go:280:13: struct of size 64 bytes could be of size 56 bytes (maligned)
	table := []struct {
	           ^
types/time_test.go:319:13: struct of size 64 bytes could be of size 56 bytes (maligned)
	table := []struct {
	           ^
types/time_test.go:510:13: struct of size 80 bytes could be of size 64 bytes (maligned)
	table := []struct {
	           ^
types/time_test.go:658:11: struct of size 40 bytes could be of size 32 bytes (maligned)
	tbl := []struct {
	         ^

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

• master