basic|boot: silence Wunterminated-string-initialization gcc15 warnings

basic|boot: silence Wunterminated-string-initialization gcc15 warnings

gcc15 has -Wunterminated-string-initialization in -Wextra and
warns about string constants that are not null terminated even though
the functions do do out of bounds access.
Silence the warnings by simply not providing an explicit size.

(cherry picked from commit af1a6db58fde8f64edcf7d27e1f3b636c999934c)