[MSA] Fix SRDF Initialization Bug / Copy Paste Error

[DLu]

Description

Fix two bugs found by @mikeferguson

• In my helper method DoubleListWidget::getSelectedValues(), I was initializing the size of the vector, not reserving it, resulting in blank strings added to the vector.
• The code for PlanningGroupsWidget::saveLinksScreen() had a copy/paste error from saveJointsScreen

Checklist

• Required by CI: Code is auto formatted using clang-format
• Extend the tutorials / documentation reference
• Document API changes relevant to the user in the MIGRATION.md notes
• Create tests, which fail without this PR reference
• Include a screenshot if changing a GUI
• While waiting for someone to review your request, please help review another open pull request to support the maintainers

[mergify]

Please target the main branch for development, we will backport the changes to feature/msa for you if approved and if they don't break API.

[codecov]

Codecov Report

Merging #1381 (7d0f9f0) into feature/msa (bd49e18) will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff              @@
##           feature/msa    #1381   +/-   ##
============================================
  Coverage        61.56%   61.56%           
============================================
  Files              274      274           
  Lines            24965    24965           
============================================
  Hits             15368    15368           
  Misses            9597     9597           

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