firstboot: drop waiting for key when starting

We only show this blurb on the first question, but the first question is
interactive anyway, hence no need to wait for input first explicitly, we
won't progress anyway without user input.

(similar for homectl's firstboot)

src/firstboot/firstboot.c

@@ -147,9 +147,7 @@ static void print_welcome(int rfd, sd_varlink **mute_console_link) {
                 fputs(glyph(GLYPH_SPARKLES), stdout);
                 putchar(' ');
         }
-        printf("Please configure your new system!\n");
-
-        any_key_to_proceed();
+        printf("Please configure your new system!\n\n");
 
         done = true;
 }