feat: set proposer-based rewards to 0

[rootulp]

Closes celestiaorg/celestia-app#1589

I briefly considered overriding these params in celestia-app similar to what we do for the gov module here but that's a messier diff and the diff introduced in this PR won't be difficult to resolve b/c upstream has deprecated these pararms in cosmos#12876. Tests in this PR were updated based on cosmos#12876.

Note: no Mainnet milestone exists in this repo but this is needed for Mainnet.

[rootulp]

It seems a little silly that it's easier to override default params like this in our fork of Cosmos SDK rather than in the app repo but it appears common per this search

[evan-forbes]

cool, thanks for the info. Its only the defaults anyway

[codecov-commenter]

Codecov Report

Merging #309 (7ea8885) into release/v0.46.x-celestia (472f7a7) will decrease coverage by 0.17%.
The diff coverage is 68.58%.

@@                     Coverage Diff                      @@
##           release/v0.46.x-celestia     #309      +/-   ##
============================================================
- Coverage                     65.69%   65.52%   -0.17%     
============================================================
  Files                           679      666      -13     
  Lines                         72212    70980    -1232     
============================================================
- Hits                          47439    46512     -927     
+ Misses                        22108    21891     -217     
+ Partials                       2665     2577      -88     

Impacted Files	Coverage Δ
baseapp/abci.go	60.53% <0.00%> (-0.44%)	⬇️
baseapp/baseapp.go	78.61% <0.00%> (-0.36%)	⬇️
baseapp/options.go	59.64% <0.00%> (-1.07%)	⬇️
client/flags/flags.go	19.04% <ø> (ø)
crypto/armor.go	82.96% <ø> (ø)
crypto/keyring/keyring.go	63.04% <ø> (ø)
server/config/toml.go	66.66% <ø> (ø)
server/mock/store.go	17.92% <0.00%> (-0.35%)	⬇️
server/rollback.go	0.00% <0.00%> (ø)
store/cachekv/internal/mergeiterator.go	0.00% <0.00%> (ø)
... and 31 more

... and 1 file with indirect coverage changes

[liamsi]

I would have expected that these two can simply be deleted as we do not need to be backwards compatible at all. But I guess for the sake of minimal changes to the upstream SDK, this is the more reasonable approach still.

Q: These would still be changeable via governance though?

[evan-forbes]

These would still be changeable via governance though?

yes, this is only changing the defaults

[rootulp]

We can delete the params if that's preferred. I set the params to zero b/c the PR in the description above and the issue @liamsi created:

In case we launch with 0.46, we should set the param to 0

[rootulp]

Will merge this as-is b/c I don't see any blocking feedback.