fix: simplify feemarket based on AIMD paper (backport #94)

[mergify]

• remove targetUtilization param (always 0.5 * maxUtilization)
• rename theta -> gamma
• set proper bounds on parameters

https://arxiv.org/pdf/2110.04753

---

This is an automatic backport of pull request #94 done by Mergify.

[mergify]

Cherry-pick of 7b6193a has failed:

On branch mergify/bp/sdk-47/pr-94
Your branch is up to date with 'origin/sdk-47'.

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  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
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Changes to be committed:
	modified:   api/feemarket/feemarket/v1/genesis.pulsar.go
	modified:   api/feemarket/feemarket/v1/params.pulsar.go
	modified:   api/feemarket/feemarket/v1/query.pulsar.go
	modified:   api/feemarket/feemarket/v1/query_grpc.pb.go
	modified:   api/feemarket/feemarket/v1/tx_grpc.pb.go
	modified:   docs/SPEC.md
	modified:   proto/feemarket/feemarket/v1/genesis.proto
	modified:   proto/feemarket/feemarket/v1/params.proto
	modified:   proto/feemarket/feemarket/v1/query.proto
	modified:   tests/e2e/consumer.go
	modified:   tests/e2e/e2e_test.go
	modified:   tests/e2e/suite.go
	modified:   x/feemarket/ante/fee.go
	modified:   x/feemarket/fuzz/aimd_eip1559_test.go
	modified:   x/feemarket/fuzz/eip1559_test.go
	modified:   x/feemarket/keeper/feemarket_test.go
	modified:   x/feemarket/keeper/keeper_test.go
	modified:   x/feemarket/keeper/query_server_test.go
	modified:   x/feemarket/types/eip1559.go
	modified:   x/feemarket/types/eip1559_aimd.go
	modified:   x/feemarket/types/genesis.pb.go
	modified:   x/feemarket/types/params.go
	modified:   x/feemarket/types/params.pb.go
	modified:   x/feemarket/types/params_test.go
	modified:   x/feemarket/types/state.go
	modified:   x/feemarket/types/state_fuzz_test.go
	modified:   x/feemarket/types/state_test.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   tests/e2e/go.mod
	both modified:   tests/e2e/go.sum
	both modified:   tests/e2e/setup.go
	both modified:   tests/integration/integration_test.go
	both modified:   x/feemarket/ante/expected_keepers.go
	both modified:   x/feemarket/ante/suite/suite.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally