Fix gantt chart swimlane order

[shefalijoshi]

Closes VIPERGC-652

Describe your changes:

Since the plan view is used by both objects of type plan and gantt chart, use the plan object to get swim lane order.
This will ensure that both views work correctly.

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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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Reviewer Checklist

• Changes appear to address issue?
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• Code style and in-line documentation are appropriate?

[codecov]

Codecov Report

Attention: Patch coverage is 25.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 57.43%. Comparing base (7c2bb16) to head (b9eef3b).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/plugins/plan/components/PlanView.vue	25.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7895      +/-   ##
==========================================
- Coverage   62.54%   57.43%   -5.12%     
==========================================
  Files         434      676     +242     
  Lines       13592    27355   +13763     
  Branches        0     2685    +2685     
==========================================
+ Hits         8501    15710    +7209     
- Misses       5091    11308    +6217     
- Partials        0      337     +337     

Flag	Coverage Δ
e2e-ci	62.47% <ø> (+0.01%)	⬆️
e2e-full	41.78% <ø> (+18.31%)	⬆️
unit	49.30% <25.00%> (?)

Files with missing lines	Coverage Δ
src/plugins/plan/components/PlanView.vue	59.32% <25.00%> (ø)

... and 371 files with indirect coverage changes

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[jvigliotta]

Looks good to me!