perf: try vec_c -> c on 3 time_values

As `vec_c` is slower on 3 scalar `Date`s, and it's probably pretty uncommon to
use `time_value`s with `c` incompatible with `vec_c` (though possible... maybe
tibbles with year, week, wday, like from MMWRweek; though these would probably
break inside archive DT).

Author: brookslogan

R/epi_slide_opt_edf.R

@@ -231,8 +231,8 @@ epi_slide_opt_one_epikey <- function(inp_tbl,
     range = vec_rep_each(
       c(FALSE, TRUE, FALSE),
       time_minus_time_in_n_steps(
-        vctrs::vec_c(out_t_min,   out_t_max, slide_t_max),
-        vctrs::vec_c(slide_t_min, out_t_min, out_t_max),
+        c(out_t_min,   out_t_max, slide_t_max),
+        c(slide_t_min, out_t_min, out_t_max),
         time_type
       ) + c(0L, 1L, 0L)
     ),