Rename the scripts that update the policy files

script/commit-current-upstream-policy-docs is now
script/write-upstream-policy-files: it writes the policy files and
commits nothing. script/update-policy is now
script/commit-upstream-policy-files, and make update-policy is now
make commit-upstream-policy-files. test/update-policy.sh follows.
Behaviour is unchanged.

Model: opus-5-5

Dockerfile

@@ -42,7 +42,7 @@ RUN script/bootstrap
 
 COPY . .
 
-RUN timeout 90 test/update-policy.sh
+RUN timeout 90 test/commit-upstream-policy-files.sh
 
 # Development environment, and the last stage: a plain `docker build .`
 # names no target and so builds this one. Nothing is wanted from the two