[SPARK-26294][CORE]Delete Unnecessary If statement

[wangjiaochun]

What changes were proposed in this pull request?

Delete unnecessary If statement, because it Impossible execution when
records less than or equal to zero.it is only execution when records begin zero.
...................
if (inMemSorter == null || inMemSorter.numRecords() <= 0) {
return 0L;
}
....................
if (inMemSorter.numRecords() > 0) {
.....................
}

How was this patch tested?

Existing tests

(Please explain how this patch was tested. E.g. unit tests, integration tests, manual tests)
(If this patch involves UI changes, please attach a screenshot; otherwise, remove this)

Please review http://spark.apache.org/contributing.html before opening a pull request.

[HyukjinKwon]

@wangjiaochun, I think you better stop fixing trivial stuff in each PR. Those stuff can be fixed when the codes around here is fixed, or let other people fix it later.

[srowen]

These aren't worth the time it takes us to review them and merge them, honestly. Little cleanup can be OK if it makes an appreciable difference in speed or readability, and if you can find many instances of the same issue.

[SparkQA]

Test build #4456 has finished for PR 23247 at commit d5aea03.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[wangjiaochun]

ok! thanks, I will focus on commit bug later.originally intended to put these trivial stuff in a PR，but worrying about unclear descriptions, so using multiple PR, It will not happen later @HyukjinKwon @srowen

[srowen]

Merged to master