test/e2e/staking to system tests

[JulianToledano]

• Find an e2e test from tests/e2e that looks like a system test.
• Rewrite it as a system test and verify it runs with v1 and v2 (CI does that)
• Delete the old e2e test.

[JulianToledano]

There is already a staking system test that is quite similar to the e2e test. However, the e2e test also checks for validator_updates in block-results. I've been trying to replicate that functionality without success, as I always get null validator_updates for the upcoming blocks. It turns out that the same issue is occurring in the e2e test, but we are not checking for the error.

cosmos-sdk/tests/e2e/staking/suite.go

Lines 100 to 122 in bed3ac0

	// Loop until we find a block result with the correct validator updates.
	// By experience, it happens around 2 blocks after `delHeight`.
	_ = s.network.RetryForBlocks(func() error {
	latestHeight, err := s.network.LatestHeight()
	require.NoError(err)
	res, err := rpcClient.BlockResults(context.Background(), &latestHeight)
	if err != nil {
	return err
	}
	if len(res.ValidatorUpdates) == 0 {
	return errors.New("validator update not found yet")
	}
	valUpdate := res.ValidatorUpdates[0]
	require.Equal(
	valUpdate.PubKeyBytes,
	val.GetPubKey().Bytes(),
	)
	return nil
	}, 10)
	}