Fix gencode indexer to detect unsigned SignedSource files

Summary:
The Glean Python gencode indexer's `GENERATED_PATTERN` regex only matched the signed form `generated SignedSource<<HEX>>`, missing ~8,000+ files that have the unsigned placeholder `generated <<SignedSource::TOKEN>>`. These files are legitimately generated but invisible to the `gencode.GenCode` Glean predicate, leaving them unprotected by `DenyIfGleanGeneratedDeadCodeClassifierRule` in the Dead Code Bot classifier pipeline. This was discovered when D99778344 deleted a generated bloks file that should have been blocked.

The regex is updated to also match the `<<SignedSource::TOKEN>>` format via an alternation. Files matching this format produce a GenCode fact with no signature (correct — the token is a placeholder, not a real hash). The OCaml/Hack indexer already handled this correctly due to a trailing `.*$` in its regex.

Reviewed By: donsbot

Differential Revision: D100816292

fbshipit-source-id: fbf48fae587aae613d52106ce38758808b9e32ed

Author: Claudionor Santos

pyrefly/lib/report/glean/convert.rs

@@ -307,7 +307,7 @@ impl GleanState<'_> {
 
     fn gencode_fact(&mut self) -> Option<gencode::GenCode> {
         let generated_pattern = RegexBuilder::new(
-            r"^.*@(?P<tag>(partially-)?generated)( SignedSource<<(?P<sign>[0-9a-f]+)>>)?$",
+            r"^.*@(?P<tag>(partially-)?generated)( (?:SignedSource<<(?P<sign>[0-9a-f]+)>>|<<SignedSource::[^>]+>>))?$",
         )
         .multi_line(true)
         .build()