[jest-each]: Add flag to prevent done callback being supplied to describe

[mattphillips]

Summary

Currently jest-each assumes if a test callback has more arguments than supplied in the data (array/template) then the extra argument is a done callback. This logic should not apply for describe blocks as they do not support done callbacks (or any args for that matter).

Fixes: #6838

Test plan

Updated unit tests to check describe blocks aren't invoked with done

[thymikee]

nit: can we fold it to:

return supportsDone && params.length < test.length 
  ? done => test(...params, done)
  : () => test(...params)

same suggestion for applyObjectParams below

[mattphillips]

Like it! may as well drop the return too 😜 what do you think of this?

const applyRestParams = (
  supportsDone: boolean,
  params: Array<any>,
  test: Function,
) => supportsDone && params.length < test.length
  ? done => test(...params, done)
  : () => test(...params);

[thymikee]

Yea, I usually have a lint rule to fix it for me :p

[codecov-io]

Codecov Report

Merging #6843 into master will decrease coverage by <.01%.
The diff coverage is 82.35%.

@@            Coverage Diff             @@
##           master    #6843      +/-   ##
==========================================
- Coverage   63.43%   63.42%   -0.01%     
==========================================
  Files         235      235              
  Lines        9115     9114       -1     
  Branches        4        4              
==========================================
- Hits         5782     5781       -1     
  Misses       3332     3332              
  Partials        1        1

Impacted Files	Coverage Δ
packages/jest-jasmine2/src/each.js	0% <0%> (ø)	⬆️
packages/jest-each/src/bind.js	86.58% <100%> (-0.17%)	⬇️
packages/jest-each/src/index.js	77.77% <100%> (ø)	⬆️
packages/jest-circus/src/index.js	57.69% <100%> (ø)	⬆️

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[github-actions]

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