Monitor indexes bloat

[0xgouda]

We should add a new metric and panels that visualize the ratio of bloat for db indexes, probably in the form Top $n indexes by bloat ratio.

[pashagolub]

Don't we have that information under table overview panels?

[0xgouda]

Don't we have that information under table overview panels?

No, we don't. We only have Index Sizes Treemap in the pg dashboard, and nothing related to indexes in the prom dashboard.