Followup: a3f58964

Restarting scanning has a fixed cost. Since we build a string
from many small parts, that causes the scan to restart many times.

It's much faster to ignore the coderange, if it's needed later it
will be faster to scan it in one go.

```
compare-ruby: ruby 3.4.0dev (2024-09-04T11:54:06Z opt-strftime-growth 149480f0ff) +YJIT [arm64-darwin23]
built-ruby: ruby 3.4.0dev (2024-09-04T11:55:26Z opt-strftime-coder.. 29a5153cba) +YJIT [arm64-darwin23]
warming up...

|                            |compare-ruby|built-ruby|
|:---------------------------|-----------:|---------:|
|time.strftime("%FT%T")      |      1.870M|    2.225M|
|                            |           -|     1.19x|
|time.strftime("%FT%T.%3N")  |      1.731M|    2.068M|
|                            |           -|     1.19x|
|time.strftime("%FT%T.%6N")  |      1.744M|    2.073M|
|                            |           -|     1.19x|
```

Cumulative with a3f58964:

```
compare-ruby: ruby 3.4.0dev (2024-09-04T11:55:26Z opt-strftime-coder.. 29a5153cba) +YJIT [arm64-darwin23]
built-ruby: ruby 3.4.0dev (2024-09-04T12:57:30Z opt-strftime-coder.. 2b938d667a) +YJIT [arm64-darwin23]
warming up...

|                            |compare-ruby|built-ruby|
|:---------------------------|-----------:|---------:|
|time.strftime("%FT%T")      |      1.784M|    2.277M|
|                            |           -|     1.28x|
|time.strftime("%FT%T.%3N")  |      1.504M|    2.056M|
|                            |           -|     1.37x|
|time.strftime("%FT%T.%6N")  |      1.489M|    2.094M|
|                            |           -|     1.41x|
```