Index set > Shard routing > Shard Popovers stack ontop of each other

While browsing the Shard Routing section of a specific index within an Index set, left-clicking on Shards to discover which OpenSearch Data nodes they were being hosted by, I noticed that the Popovers that provide this information appear to stack on-top of each other.

https://github.com/user-attachments/assets/ebc0bb0b-2ca5-4540-b967-059718223567

Technically nothing is wrong, yet visually this can appear to be confusing.

## Expected Behavior

It easily could just be my perspective, but I imagine that a natural expectation of clicking thru shards is for only one Popover to be displayed at any given time. And the action of left-clicking on a Shard to display the Popover, should 1st remove any existing Popovers before displaying a new one.

In the context of the video illustration, a total of 6 shards were in-use. Imagine for example, cases where clients might have an Index set whose Shard-strategy defines 20 or more shards. When an Operator would left-click multiple Shards only once, they could easily accumulate a stack of Popovers that might be impossible to "clear" without refreshing the page. While this likely would not cause any loss of data, as no fields are exposed for editing in this state, refreshing the page to clear the Popovers seems excessive to expect an Operator to manage the stack of Popovers with.

## Current Behavior

When clicking on a Shard to display its routing-information, a Popover is displayed. This action is honored no matter whether any Popovers are already displayed. And the end result of clicking thru multiple Shards is a stack of Popovers which can then create a visually confusing image.

## Possible Solution

Perhaps we could consider the idea of insuring only 1 Shard Routing-information Popover is displayed at any given time.

## Steps to Reproduce (for bugs)

1. Create an Index set of >= 6 shards (the Primary+Secondary count should not matter).
2. Goto System > Indices, then left-click on the target Index set (created by the previous step).
3. Left-click on "Show Details / Actions" beside an Index in the set.
4. Confirm that the "Shard routing" section displays >= 6 shards.
5. From left-to-right, left-click 1x once on each Shard displayed. Notice the Popovers begin stacking on-top of each other.

## Context

While no real issue was caused for me by this problem, it was visually confusing.

## Your Environment

* Graylog Version: 6.3.7
* Java Version: Java 21
* OpenSearch Version: 2.19.3
* MongoDB Version: 7.0.23
* Operating System: Debian 13 (Trixie)
* Browser version: Brave 1.84.132

## Checklist
[] This issue fix need to be backported.
[] Does this issue have **security** implications?