Improve Fleet performance

[aruiz14]

Summary

Issue #12895

Performance improvements while keeping the same behavior.

Occurred changes and/or fixed issues

(Changes are logically split into different commits)

• Standardize on clusterID vs. "clusterLabel" (which normally refers to the management Cluster resource name, while the Fleet Cluster name is usually the same as the "display" name).
  • The clusterId is compound by ${namespace}/${name} of the Cluster resource, making it easier to work with.
  • The management "Cluster" object (clusterLabel) is only really needed for calculating the detailLocation of deployed resouces, as they will link to the Explorer, which uses the management clusters' names.
• Refactor usages of clusterResourceStatus, which is always combined with a find by clusterLabel (now clusterId).
  • Used to obtain the resource statuses count per cluster.
  • Used to get the cluster state (based in the resource statuses aggregation).
  • This was being performed for every cluster individually, so it impacts performance exponentially to the number downstream clusters.
  • Reworking this allows to finally get rid of this function completely 🎉 .
• The Continuous Delivery dashboard iterates over all gitrepos/bundles/clusters in order obtain the badges and tooltip for every single entry in the table.
  • I've computed the necessary information in a single place and passed it to the relevant functions so they can easily pick what they need, hence greatly reducing the number of iterations (see screenshot below)
• Small optimizations (e.g. use a variable to avoid calling the same getters multiple times within the same function).

Technical notes summary

Above changes were driven by capturing and analyzing Performance traces with the Chrome Dev Tools, on a local Rancher installation where many sample workloads were installed.
See a summary of CPU usage over 30s of loading the CD dashboard:

• Before:
  
• After:
  

Areas or cases that should be tested

• Continuous Delivery:
  • Dashboard
  • Cluster list
  • Cluster details
  • GitRepo list
  • GitRepo details

Areas which could experience regressions

These changes aim for improving performance while not introducing any changes to the information being displayed.
I've performed several tests using a local UI build and couldn't find any difference, but I may have missed something.

Checklist

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