refactor: use handlebars triple escapes in templates (#1434)

lib/config/definitions.js

lib/config/templates/default/branch-name.hbs

lib/config/templates/default/commit-message.hbs

lib/config/templates/default/pr-body.hbs

lib/config/templates/default/pr-title.hbs

lib/config/templates/docker-digest/branch-name.hbs

lib/config/templates/docker-digest/commit-message.hbs

lib/config/templates/docker-digest/pr-body.hbs

lib/config/templates/docker-digest/pr-title.hbs

lib/config/templates/docker-group/pr-body.hbs

lib/config/templates/docker-group/pr-title.hbs

lib/config/templates/docker-pin-group/pr-body.hbs

lib/config/templates/docker-pin/branch-name.hbs

lib/config/templates/docker-pin/pr-body.hbs

lib/config/templates/docker-pin/pr-title.hbs

lib/config/templates/docker/branch-name.hbs

lib/config/templates/docker/commit-message.hbs

lib/config/templates/docker/pr-body.hbs

lib/config/templates/docker/pr-title.hbs

lib/config/templates/group/branch-name.hbs