fix(pilota-thrift-parser): trim extra whitespace characters at the end of annotation list item

[Ggiggle]

Motivation

The previous annotations‘ parser was not compatible with extra null characters at the end of the list. Thus, the apache thrift test data would encounter error for its blank after the last list item.

Solution

We will identify and remove whitespace characters at the end of the list item. Considering multiple list parsing scenarios, we choose to remove whitespace characters in the extraction of each list item separator, although these characters may have been extracted in the outer layer.