Table: Update UX for uniform-reducer case in new footer and overflow (#110493)

* Table: Update UX for single-reducer use case in new footer

* all cases are working; unit tests pass

* style and code cleanup in SummaryCell

* remove e2e test for sum reducer label

* reorganize code, todo tests

* slight style cleanup

* one more little reorganization

* updates based on CI failures

* update tests and docs

* unused prop

* update table footer image

* alt text, lint issue

* update gdev to create footer dashboard and re-point e2es there, add a few new cases

* remove console.log

devenv/jsonnet/dev-dashboards.libsonnet

@@ -94,6 +94,7 @@
     "rows-to-fields": (import '../dev-dashboards/transforms/rows-to-fields.json'),
     "shared_queries": (import '../dev-dashboards/panel-common/shared_queries.json'),
     "slow_queries_and_annotations": (import '../dev-dashboards/scenarios/slow_queries_and_annotations.json'),
+    "table_footer": (import '../dev-dashboards/panel-table/table_footer.json'),
     "table_kitchen_sink": (import '../dev-dashboards/panel-table/table_kitchen_sink.json'),
     "table_markdown": (import '../dev-dashboards/panel-table/table_markdown.json'),
     "table_pagination": (import '../dev-dashboards/panel-table/table_pagination.json'),