[Bug]: referral program taker fee discounts on trade event where referrer below min stake

[Sohill-Patel]

Problem encountered

referee taker fee discount showing on trade when referrer has no stake

If a referrer removes sufficient stake to not meet the required tokens, the referral set should not be eligible for the following referral benefits:
- the referrer should not be rewarded for any referee taker fees (0083-RFPR-018).
- all referees should not receive any discount on their taker fees (0083-RFPR-019).

Observed behaviour

taker fee discount showing on BUS_EVENT_TYPE_TRADE

{"id":"331-19","block":"F99A9664639E9818AD68F816805485F5D1CD6F603F52BF3AB936CF64186FB354","type":"BUS_EVENT_TYPE_TRADE","trade":{"id":"e4b28f5ecb65cac7b09a38be1d29bd32a66fd7411516aa3f047ac6ecfebcaed4","marketId":"bcd520534a681052235c1dd44c2d266a70accf4a8b680e753e8d1ac5dd3e25c6","price":"100000000","size":"5000000","buyer":"14cfcc3571fa6425f4dc0b6112595d6e6f13cd390c7028c9799eaa9c805368e1","seller":"a8fe5ebc9d8aa68de87e37bac20f38d85297de1ab421456fcd35727ad0c1dcc6","aggressor":"SIDE_SELL","buyOrder":"1c467375309cd6080aef927cb80878bba1cf6f2ffa08b31ce34b331de1753d03","sellOrder":"41162b6f29c5dbde7ffe0d81f6e68bf1f673f70111d6ed7c678a5778578e291f","timestamp":"1697192450878512569","type":"TYPE_DEFAULT","buyerFee":{"makerFee":"0","infrastructureFee":"0","liquidityFee":"0","makerFeeVolumeDiscount":"0","infrastructureFeeVolumeDiscount":"0","liquidityFeeVolumeDiscount":"0","makerFeeReferrerDiscount":"0","infrastructureFeeReferrerDiscount":"0","liquidityFeeReferrerDiscount":"0"},"sellerFee":{"makerFee":"199600000000000000000","infrastructureFee":"49900000000000000000","liquidityFee":"14970000000000000000000","makerFeeVolumeDiscount":"0","infrastructureFeeVolumeDiscount":"0","liquidityFeeVolumeDiscount":"0","makerFeeReferrerDiscount":"400000000000000000","infrastructureFeeReferrerDiscount":"100000000000000000","liquidityFeeReferrerDiscount":"30000000000000000000"}},"version":1,"chainId":"testnet-001","txHash":"9A0736165C01FBF8E6FDC911D887EC64977FAE7EC537B5779CF918AE15D22369"}

Expected behaviour

i would expect the BUS_EVENT_TYPE_TRADE to show taker fee discounts of 0

Steps to reproduce

1. run system-test `test_referral_set_referrer_bug`

Software version

dev branch

Failing test

test_referral_set_referrer_bug

Jenkins run

https://jenkins.vega.rocks/job/common/job/system-tests-wrapper/23171/

Configuration used

No response

Relevant log output

No response

[ze97286]

but the discount factor will only be updated for the following epoch - i.e. if some party withdraws their stake during an epoch, they will still be eligible for the discount until the epoch ends. This could be changed is required cc @cdummett

[Sohill-Patel]

The test scenario is like this:

referral set created with referrer(with stake) and referee
referral program is created
remove stake from referrer
wait an epoch
check referrer has no stake

trade1 - referee is taker
wait an epoch
trade2 again - referee is taker
wait for epoch <- added this so I can check ledger for referrer rewards (there is none as expected)
check trade2 for taker fees <- the test fails here because it expects no taker fee discount here

[ze97286]

thanks @Sohill-Patell, fix on the way.