Fix achievements response parsing

[maskaravivek]

Description (required)

Fixes #2271
Fixes #2284

What changes did you make and why?

There was some issue with how the JSON was getting parsed. The issue was introduced in #2287.

Tests performed (required)

prodDebug

Screenshots showing what changed (optional - for UI changes)

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@aac0b7c). Click here to learn what that means.
The diff coverage is 0%.

@@           Coverage Diff            @@
##             master   #2323   +/-   ##
========================================
  Coverage          ?   5.89%           
========================================
  Files             ?     237           
  Lines             ?   11354           
  Branches          ?    1020           
========================================
  Hits              ?     669           
  Misses            ?   10633           
  Partials          ?      52

Impacted Files	Coverage Δ
...rw/commons/mwapi/ApacheHttpClientMediaWikiApi.java	3.94% <0%> (ø)

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