[C++] Disambiguate function calls in csv parser test

[asfimport]

cpp/src/arrow/csv/parser_test.cc has calls to overloaded functions which cannot be disambiguated. see #5727

Reporter: Prudhvi Porandla / @pprudhvi
Assignee: Prudhvi Porandla / @pprudhvi

PRs and other links:

• GitHub Pull Request #5791

_{Note: This issue was originally created as ARROW-7099. Please see the migration documentation for further details.}

[asfimport]

Francois Saint-Jacques / @fsaintjacques:
Issue resolved by pull request 5791
#5791