Disable javadoc job for jaeger-thrift

[vprithvi]

jaeger-thrift only contains generated sources, and the existing excludes in build.gradle weren't effective.

[codecov-io]

Codecov Report

Merging #245 into master will decrease coverage by 0.14%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #245      +/-   ##
============================================
- Coverage     82.02%   81.87%   -0.15%     
+ Complexity      526      524       -2     
============================================
  Files            87       87              
  Lines          2003     2003              
  Branches        236      236              
============================================
- Hits           1643     1640       -3     
- Misses          262      263       +1     
- Partials         98      100       +2

Impacted Files	Coverage Δ	Complexity Δ
...jaeger/reporters/protocols/ThriftUdpTransport.java	77.96% <0%> (-5.09%)	14% <0%> (-2%)

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