[SPARK-12327] Disable commented code lintr temporarily

cc yhuai felixcheung shaneknapp

Author: Shivaram Venkataraman <shivaram@cs.berkeley.edu>

Closes #10300 from shivaram/comment-lintr-disable.

R/pkg/.lintr

-linters: with_defaults(line_length_linter(100), camel_case_linter = NULL, open_curly_linter(allow_single_line = TRUE), closed_curly_linter(allow_single_line = TRUE))
+linters: with_defaults(line_length_linter(100), camel_case_linter = NULL, open_curly_linter(allow_single_line = TRUE), closed_curly_linter(allow_single_line = TRUE), commented_code_linter = NULL)
 exclusions: list("inst/profile/general.R" = 1, "inst/profile/shell.R")