[SPARK-3010] fix redundant conditional

https://issues.apache.org/jira/browse/SPARK-3010

this pr is to fix redundant conditional in spark, such as
1.
private[spark] def codegenEnabled: Boolean =
if (getConf(CODEGEN_ENABLED, "false") == "true") true else false
2.
x => if (x == 2) true else false
...

Author: scwf <wangfei1@huawei.com>
Author: wangfei <wangfei_hello@126.com>

Closes #1992 from scwf/condition and squashes the following commits:

b2a044a [scwf] merge SecurityManager
e16239c [scwf] fix confilct
6811401 [scwf] fix merge confilct
0824df4 [scwf] Merge branch 'master' of https://github.com/apache/spark into patch-4
e274515 [scwf] fix redundant conditions
d032bf9 [wangfei] [SQL]Excess judgment