Bug 1643504 - Upgrade the Linux64 generate-profile task to Debian buster. r=firefox-build-system-reviewers,rstewart

Differential Revision: https://phabricator.services.mozilla.com/D78427

taskcluster/ci/generate-profile/kind.yml

@@ -67,7 +67,7 @@ jobs:
             env:
                 NEED_XVFB: "true"
             max-run-time: 1200
-            docker-image: {in-tree: debian9-amd64-build}
+            docker-image: {in-tree: debian10-amd64-build}
             artifacts:
                 - type: directory
                   name: public/build