perf: avoid c.Date when possible

Revert earlier change to try to reduce time inside `time_minus_time_in_n_steps`,
as `c.Date` is more costly.  This also works back towards generality from the
previous `vec_c` -> `c` change.

Author: brookslogan

R/epi_slide_opt_edf.R

@@ -230,11 +230,9 @@ epi_slide_opt_one_epikey <- function(inp_tbl,
     out_filter_time_style,
     range = vec_rep_each(
       c(FALSE, TRUE, FALSE),
-      time_minus_time_in_n_steps(
-        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)
+      c(time_minus_time_in_n_steps(out_t_min, slide_t_min, time_type),
+        time_minus_time_in_n_steps(out_t_max, out_t_min, time_type) + 1L,
+        time_minus_time_in_n_steps(slide_t_max, out_t_max, time_type))
     ),
     set = vec_in(slide_time_values, out_time_values)
   )