Add reporting assets to the eslint ignore file (elastic#69968) (elastic#70013)

Author: Joel Griffith

.eslintignore

@@ -33,6 +33,7 @@ target
 /x-pack/plugins/canvas/shareable_runtime/build
 /x-pack/plugins/canvas/storybook
 /x-pack/plugins/monitoring/public/lib/jquery_flot
+/x-pack/plugins/reporting/server/export_types/printable_pdf/server/lib/pdf/assets/**
 /x-pack/legacy/plugins/infra/common/graphql/types.ts
 /x-pack/legacy/plugins/infra/public/graphql/types.ts
 /x-pack/legacy/plugins/infra/server/graphql/types.ts