Variables: In ssm source auto parse only object JSON notation

[medikoo]

Closes: #9742

[codecov]

Codecov Report

Merging #9747 (25c7ce8) into master (7078449) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #9747   +/-   ##
=======================================
  Coverage   86.10%   86.10%           
=======================================
  Files         328      328           
  Lines       12590    12591    +1     
=======================================
+ Hits        10840    10841    +1     
  Misses       1750     1750           

Impacted Files	Coverage Δ
...on/variables/sources/instance-dependent/get-ssm.js	91.11% <100.00%> (+0.20%)	⬆️

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[pgrzesik]

Great call, change looks good 👍