fix(perp): emit MarketUpdatedEvents even in the absence of index price

[k-yang]

Description

Emit MarketUpdatedEvent and AmmUpdatedEvent even if there is no valid index price.

Purpose

• Closes fix: MarketUpdated and AmmUpdated events should still be published in the absence of an index price #1561

[codecov]

Codecov Report

Merging #1606 (25a3253) into master (8f9c4ca) will increase coverage by 0.41%.
Report is 3 commits behind head on master.
The diff coverage is 83.03%.

@@            Coverage Diff             @@
##           master    #1606      +/-   ##
==========================================
+ Coverage   74.08%   74.49%   +0.41%     
==========================================
  Files         175      175              
  Lines       14268    14567     +299     
==========================================
+ Hits        10570    10852     +282     
- Misses       3096     3097       +1     
- Partials      602      618      +16     

Files	Coverage Δ
app/keepers.go	99.20% <100.00%> (ø)
x/tokenfactory/keeper/grpc_query.go	91.89% <100.00%> (+73.28%)	⬆️
x/tokenfactory/keeper/store.go	100.00% <100.00%> (ø)
x/tokenfactory/types/codec.go	100.00% <100.00%> (ø)
x/tokenfactory/types/errors.go	100.00% <ø> (ø)
x/tokenfactory/types/genesis.go	100.00% <100.00%> (+10.71%)	⬆️
x/perp/v2/module/abci.go	65.00% <85.71%> (+1.84%)	⬆️
x/tokenfactory/types/tx_msgs.go	97.16% <94.73%> (-2.84%)	⬇️
x/tokenfactory/cli/tx.go	80.12% <80.95%> (-3.44%)	⬇️
x/tokenfactory/keeper/msg_server.go	82.00% <76.08%> (-13.17%)	⬇️

... and 1 file with indirect coverage changes