Fix plot duplication and purging logic

[shefalijoshi]

Closes #7926

Describe your changes:

1. Duplicate data was not being properly eliminated due to outdated use of lodash utility uniq. Replaced that with the right .sortedUniqBy
2. Faulty logic when records out of range are being purged. Fixed that logic to take into account in-place data modification.

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• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Is this a notable change that will require a special callout in the release notes? For example, will this break compatibility with existing APIs or projects that consume these plugins?

Author Checklist

• Changes address original issue?
• Tests included and/or updated with changes?
• Has this been smoke tested?
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• Testing instructions included in associated issue OR is this a dependency/testcase change?

Reviewer Checklist

• Changes appear to address issue?
• Reviewer has tested changes by following the provided instructions?
• Changes appear not to be breaking changes?
• Appropriate automated tests included?
• Code style and in-line documentation are appropriate?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 57.44%. Comparing base (ea9947c) to head (538216b).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7939      +/-   ##
==========================================
- Coverage   57.66%   57.44%   -0.23%     
==========================================
  Files         677      677              
  Lines       27373    27374       +1     
  Branches     2689     2689              
==========================================
- Hits        15786    15724      -62     
- Misses      11248    11309      +61     
- Partials      339      341       +2     

Flag	Coverage Δ
e2e-ci	62.41% <100.00%> (-0.07%)	⬇️
e2e-full	41.83% <80.00%> (-16.31%)	⬇️
unit	49.27% <60.00%> (-0.08%)	⬇️

Files with missing lines	Coverage Δ
src/plugins/plot/MctPlot.vue	37.20% <ø> (ø)
src/plugins/plot/configuration/PlotSeries.js	87.24% <100.00%> (+0.57%)	⬆️
...gins/telemetryTable/TelemetryTableConfiguration.js	66.27% <100.00%> (ø)

... and 13 files with indirect coverage changes

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[jvigliotta]

This looks good to me!