Rename branch and remove -umask suffix

Other stemcell/os-image branches will not use the suffix and this keeps
us more consistent with those and other artifacts.

[#152664357](https://www.pivotaltracker.com/story/show/152664357)

ci/configure.sh

@@ -1,10 +1,10 @@
 #!/usr/bin/env bash
 
 fly -t production set-pipeline \
-    -p bosh-agent:2.47.x-umask \
+    -p bosh-agent:2.47.x \
     -c ci/pipeline.yml \
     --load-vars-from <(lpass show -G "bosh-agent concourse secrets" --notes) \
-    --var agent_branch=2.47.x-umask \
+    --var agent_branch=2.47.x \
     --var version_bump='patch' \
     --var agent_version_key='agent-2.47-current-version' \
     --var agent_initial_version=2.47.0

ci/tasks/assert-version-aligns.sh

@@ -21,7 +21,7 @@ fi
 
 echo "will only continue if version to promote matches $version_must_match ..."
 
-if ! [[ "${semver}-umask" =~ $version_must_match ]]; then
+if ! [[ $semver =~ $version_must_match ]]; then
   echo "version $semver DOES NOT ALIGN with branch $git_branch -- promote step canceled!"
   exit 1
 fi