[3.13] gh-135307: Fix email error when policy max_line_length is set to 0 or None (GH-135367) (#140917)

[3.13] gh-135307: Fix email error when policy max_line_length is set to 0 or None (GH-135367)
(cherry picked from commit 6d45cd8dbb07ae020ec07f2c3375dd06e52377f6)

Co-authored-by: Jiucheng(Oliver) <git.jiucheng@gmail.com>
RDM: Like the change made in a earlier PR to the folder, we can/must use 'maxlen' as a stand in for 'unlimited' when computing line lengths when max_line_length is 0 or None; otherwise the computation results in a traceback.