GlobalReplace with patterns ending in .*$ scans entire input through BitState unnecessarily

When using RE2::GlobalReplace with patterns ending in `.*$` (or `.*`) where the `.*` contributes no capture groups, BitState scans the entire input string to track the .* states, even though it is guaranteed to consume the rest of the string.

This is a pretty common usecase for log processing where a regex like `^https?://(?:www\.)?([^/]+)/.*$` is used to extract hostnames from web logs.

It should be possible to short-circuit the match once everything before the trailing `.*` has been matched, avoiding the cost of scanning the remainder of the input.

I prototyped this by stripping the trailing`.*$` and using `RE2::Extract` instead of `GlobalReplace`, which significantly reduced BitState CPU. However, I had to add a guard to fall back when the replacement references \0 (full match), since the matched portion changes.

Is this approach sound? Are there other edge cases or correctness issues I might be missing? Would this be worth handling natively in RE2?