QGB remove unnecessary keystore

[rach-id]

Removes the custom key_store implementation and uses existing one. Also, updates tests.
Closes #498

[rach-id]

Depends on #526

[codecov-commenter]

Codecov Report

Merging #527 (0b53330) into qgb-integration (458b6b2) will decrease coverage by 2.06%.
The diff coverage is 20.12%.

@@                Coverage Diff                 @@
##           qgb-integration    #527      +/-   ##
==================================================
- Coverage            11.72%   9.66%   -2.07%     
==================================================
  Files                   65      55      -10     
  Lines                10881    9394    -1487     
==================================================
- Hits                  1276     908     -368     
+ Misses                9515    8404    -1111     
+ Partials                90      82       -8     

Impacted Files	Coverage Δ
e2e/qgb/qgb_network.go	0.00% <0.00%> (ø)
e2e/qgb/test_commons.go	0.00% <ø> (ø)
x/qgb/keeper/hooks.go	34.61% <ø> (+2.47%)	⬆️
x/qgb/keeper/keeper_attestation.go	24.52% <0.00%> (ø)
x/qgb/keeper/keeper_data_commitment_confirm.go	42.85% <ø> (ø)
x/qgb/keeper/keeper_valset.go	32.00% <0.00%> (-7.51%)	⬇️
x/qgb/keeper/msg_server.go	0.00% <0.00%> (ø)
x/qgb/keeper/query_attestation.go	0.00% <ø> (ø)
x/qgb/keeper/query_general.go	0.00% <0.00%> (ø)
x/qgb/keeper/query_valset.go	0.00% <ø> (ø)
... and 25 more

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[evan-forbes]

lit