txt_roller: Remove domain_prefix

This is now calculated automatically (http://fxrev.dev/1117183).

Bug: b/359925419
Change-Id: I617393d0184a3a22648bd52a0fb282d4d2b523c8
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/235300
Reviewed-by: Taylor Cramer <cramertj@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Commit-Queue: Rob Mohr <mohrr@google.com>
diff --git a/recipes/txt_roller.py b/recipes/txt_roller.py
index 028efba..a24649b 100644
--- a/recipes/txt_roller.py
+++ b/recipes/txt_roller.py
@@ -66,10 +66,7 @@
 
     author_override: api.git_roll_util.Author = None
     if props.forge_author:
-        author_override = api.git_roll_util.get_author_override(
-            *rolls,
-            domain_prefix="pigweed.infra.roller",
-        )
+        author_override = api.git_roll_util.get_author_override(*rolls)
 
     change = api.auto_roller.attempt_roll(
         props.auto_roller_options,