test: more incentive test flows

[toteki]

Additional reward calculation and timing scenarios as requested

[codecov]

Codecov Report

Merging #2124 (866ad31) into main (7f05ad4) will decrease coverage by 0.91%.
The diff coverage is 77.47%.

@@            Coverage Diff             @@
##             main    #2124      +/-   ##
==========================================
- Coverage   75.38%   74.48%   -0.91%     
==========================================
  Files         100      127      +27     
  Lines        8025     9968    +1943     
==========================================
+ Hits         6050     7425    +1375     
- Misses       1589     2039     +450     
- Partials      386      504     +118     

Impacted Files	Coverage Δ
ante/spam_prevention.go	75.92% <ø> (ø)
x/incentive/codec.go	47.82% <ø> (+9.89%)	⬆️
x/incentive/keeper/invariants.go	0.00% <0.00%> (ø)
x/leverage/client/tests/suite.go	100.00% <ø> (ø)
x/leverage/client/tests/tests.go	100.00% <ø> (ø)
x/leverage/keeper/borrows.go	75.93% <ø> (-2.64%)	⬇️
x/leverage/keeper/collateral.go	72.72% <ø> (-0.16%)	⬇️
x/leverage/keeper/errors.go	100.00% <ø> (ø)
x/leverage/keeper/exchange_rate.go	72.72% <ø> (ø)
x/leverage/keeper/genesis.go	87.23% <ø> (ø)
... and 60 more

... and 29 files with indirect coverage changes

[robert-zaremba]

Flows 3,4 & 5 are not implemented: https://linear.app/umee/issue/UMEE-678/more-test-flows-for-xincentive

[robert-zaremba]

• program can have leftovers if there are people who are not bonded by the end of the program. As discussed - recovering the leftovers is not a blocker for the release, but must be documented and scheduled for the next release
• documentation: we need to clearly document what is happening when there is a gap in bonding, and when leftovers are produced
• New Test case is needed:
  • alice and bob joins before the program. Alice bonds 3x what bob bonds
  • alice exits at 20% of the time
  • bob exits at 30% of the time
  • bob rejoins at 50% of the time and stays till the end.
  • expected rewards (T = total rewards of the program):
    • alice = T*20%*3/4
    • bob = T - alice_rewards
    • so all rewards are distributed, there are no leftovers

[toteki]

Added the final test scenario

There is also documentation (in the EndBlocker functions) about what happens in the zero-bonded edge case, which I have highlighted in the diff by adding more.

[robert-zaremba]

Few final comments to improve the test.
Overall good job. Thanks @toteki and @EbrahimUmee for getting this test suite to the finish line.

[robert-zaremba]

let's make sure to fill checkboxes before merging: #2124 (review)

[robert-zaremba]

Let's move this PR to the finish line. There are few open comments which have to be solved.

[toteki]

Resolved all issues, but need to redo PR due to unsigned commits

#2141

[robert-zaremba]

replaced by: #2124