Hardcode pxf_tarball version_id

This is the same version_id used in the 5.10.0 release from the
5X-release pipeline
Co-authored-by: NJason Vigil <jvigil@pivotal.io>
Co-authored-by: NKris Macoskey <kmacoskey@pivotal.io>
Co-authored-by: NEd Espino <edespino@pivotal.io>

concourse/pipelines/5X_STABLE-generated.yml

@@ -3565,6 +3565,7 @@ jobs:
       trigger: true
     - get: pxf_tarball
       trigger: true
+      version: {version_id: Iex4xYPSamHvDCiKiaYtQ6zrRw6Faja6}
     - get: pxf_infra_src
     - get: centos6-gpdb-dev-pxf-hdp
   - task: test_pxf

concourse/pipelines/templates/gpdb-tpl.yml

@@ -3228,6 +3228,7 @@ jobs:
       trigger: [[ test_trigger ]]
     - get: pxf_tarball
       trigger: [[ test_trigger ]]
+      version: {version_id: Iex4xYPSamHvDCiKiaYtQ6zrRw6Faja6}
     - get: pxf_infra_src
     - get: centos6-gpdb-dev-pxf-hdp
   - task: test_pxf