Fix JarInfer parameter indexes for instance methods

[msridhar]

Previously, when JarInfer wrote an astubx file, it treated the receiver parameter of an instance method as being at parameter index 0. In other places we do library modeling, the receiver parameter is ignored and the next parameter is treated as being at index 0. The latter handling is more sensible for NullAway, as we have not needed to do any kind of library modeling of receiver parameters yet.

This PR switches the JarInfer logic to ignore the receiver parameter like in other places. This breaks pre-existing astubx files, so we disable an integration test for now. We will bump the astubx version and fix up existing files in a later PR as part of an overall fix to #1072 (fixing in multiple PRs to ease reviewing).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.87%. Comparing base (0a5fa0f) to head (e0ef4c7).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1071   +/-   ##
=========================================
  Coverage     87.86%   87.87%           
+ Complexity     2211     2210    -1     
=========================================
  Files            85       85           
  Lines          7188     7190    +2     
  Branches       1425     1423    -2     
=========================================
+ Hits           6316     6318    +2     
  Misses          438      438           
  Partials        434      434           

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[yuxincs]

Awesome, and thanks for splitting up the PRs!