Make `py_proto_library` use regular runfiles instead of custom runfiles provider.

This is so that the pure-Starlark Python rules can include the necessary runfiles.
The PythonRunfilesProvider isn't accessible to Starlark (and making it so appears
to be difficult). So instead, just use the regular runfiles provider, which is
more in line with how other rules pass along their runfiles.

PiperOrigin-RevId: 414475012
diff --git a/src/main/java/com/google/devtools/build/lib/rules/python/PyExecutable.java b/src/main/java/com/google/devtools/build/lib/rules/python/PyExecutable.java
index 159f499..3c54608 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/python/PyExecutable.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/python/PyExecutable.java
@@ -151,7 +151,6 @@
     builder.addArtifact(common.getExecutable());
     builder.addTransitiveArtifacts(common.getFilesToBuild());
     semantics.collectDefaultRunfiles(ruleContext, builder);
-    builder.add(ruleContext, PythonRunfilesProvider.TO_RUNFILES);
 
     maybeCreateInitFiles(ruleContext, builder, semantics);
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/python/PyLibrary.java b/src/main/java/com/google/devtools/build/lib/rules/python/PyLibrary.java
index 3bdaa0a..62d6a66 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/python/PyLibrary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/python/PyLibrary.java
@@ -59,7 +59,6 @@
     Runfiles.Builder runfilesBuilder = new Runfiles.Builder(
         ruleContext.getWorkspaceName(), ruleContext.getConfiguration().legacyExternalRunfiles());
     runfilesBuilder.addTransitiveArtifacts(filesToBuild);
-    runfilesBuilder.add(ruleContext, PythonRunfilesProvider.TO_RUNFILES);
     runfilesBuilder.addRunfiles(ruleContext, RunfilesProvider.DEFAULT_RUNFILES);
 
     RuleConfiguredTargetBuilder builder = new RuleConfiguredTargetBuilder(ruleContext);