refactor: replace onReady with data property in metric widget for Explorer

[cseas]

Description

This is a refactor of the changes added in #107 and doesn't change any functionality in the application. Check deleted comment in the code for context and motivation behind the refactor.

Testing

Todo

Checklist:

• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works

[codecov]

Codecov Report

Merging #113 (c094210) into rzp_main (dbc9a19) will decrease coverage by 23.65%.
The diff coverage is 0.00%.

@@              Coverage Diff              @@
##           rzp_main     #113       +/-   ##
=============================================
- Coverage     81.70%   58.04%   -23.66%     
=============================================
  Files           933      933               
  Lines         20133    20131        -2     
  Branches       2740     2741        +1     
=============================================
- Hits          16449    11686     -4763     
- Misses         3530     8061     +4531     
- Partials        154      384      +230     

Impacted Files	Coverage Δ
...y/src/pages/explorer/explorer-dashboard-builder.ts	12.04% <0.00%> (-77.37%)	⬇️
...ed/components/topology/utils/topology-converter.ts	2.56% <0.00%> (-97.44%)	⬇️
...ponents/radar/layout/radar-chart-layout.service.ts	6.89% <0.00%> (-93.11%)	⬇️
...rtesian/d3/scale/state/cartesian-stacking-state.ts	5.00% <0.00%> (-92.50%)	⬇️
...logy/renderers/tooltip/topology-tooltip-popover.ts	7.50% <0.00%> (-92.50%)	⬇️
.../utils/builders/request/graphql-request-builder.ts	3.48% <0.00%> (-91.87%)	⬇️
.../edge/curved/entity-edge-curve-renderer.service.ts	8.49% <0.00%> (-91.51%)	⬇️
.../components/radar/axis/radar-chart-axis.service.ts	7.29% <0.00%> (-89.59%)	⬇️
...ents/radar/series/radar-series-renderer.service.ts	11.11% <0.00%> (-88.89%)	⬇️
...s/topology/d3/interactions/hover/topology-hover.ts	8.88% <0.00%> (-88.89%)	⬇️
... and 199 more

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[github-actions]

Unit Test Results

       4 files  ±  0     301 suites   - 2   24m 24s ⏱️ + 1m 48s
1 075 tests  - 12  1 075 ✔️  - 12  0 💤 ±0  0 ❌ ±0 
1 082 runs   - 13  1 082 ✔️  - 13  0 💤 ±0  0 ❌ ±0 

Results for commit c094210. ± Comparison against base commit dbc9a19.