[FLASH-480] Fix bug: rename column

[JaySon-Huang]

If we create a table with two column, naming a,b.
Then we rename column a-> c, b -> a.
Rename will fail and error log as below

2019.09.09 17:25:42.248979 [ 3 ] <Debug> SchemaSyncer: try load schema diffs.
2019.09.09 17:25:42.249008 [ 3 ] <Debug> SchemaSyncer: end load schema diffs.
2019.09.09 17:25:42.249079 [ 3 ] <Error> SchemaBuilder: detect column a rename to c
2019.09.09 17:25:42.249123 [ 3 ] <Error> SchemaBuilder: detect column b rename to a
2019.09.09 17:25:42.249166 [ 3 ] <Debug> SchemaBuilder: void DB::SchemaBuilder<DB::MockSchemaGetter>::applyAlterTableImpl(TiDB::TableInfoPtr, const DB::String &, DB::StorageMergeTree *) [Getter = DB::MockSchemaGetter]: Detected schema changes: default.test
RENAME COLUMN from a to c, RENAME COLUMN from a to _tiflash_tmp_a, RENAME COLUMN from b to a,
2019.09.09 17:25:42.257102 [ 3 ] <Error> SchemaSyncer: apply diff meets exception : DB::Exception: Rename column fails, old column name: a doesn't exist

The second AlterCommand for rename( which rename a to _tiflash_tmp_a ) is redundant since we have already renamed column a to c at the first AlterCommand.

We should remove dependency from rename_map once its rename command has generated.

[JaySon-Huang]

/run-integration-tests

[hanfei1991]

LGTM

[JaySon-Huang]

/run-integration-tests