POST /eth/v1/validator/{pubkey}/feerecipient of an existing remotekey requires beacon-chain restart to register in the relay

[pablomendezroyo]

Describe the bug

After successfully POST feerecipient through validator keymanager API, it seems like the beacon-chain service (BN) does not register this new FeeRecipient to MEVBoost/relays. When querying the relay the validator registration data, the old FR is still there

Expected behaviour

Nimbus beacon-chain registers the new fee recipient in the relay.

To Reproduce
Steps to reproduce the behavior:

1. Platform details (OS, architecture): running nimbus as multiservice with docker.
2. Branch/commit used: nimbus version 25.1.0
3. Commands being executed: POST fee recipient endpoint. See https://ethereum.github.io/keymanager-APIs/#/Fee%20Recipient
4. Relevant log lines:

Additional context
Running nimbus in dappnode. See https://github.com/dappnode/DAppNodePackage-nimbus-generic

[pablomendezroyo]

It might be related to #5983 . But still facing the same issue

[tersec]

Related to #6412 -- i.e. the issue here is likely that it's the VC, not the BN, which knows about this, since the in-BN version of this should be fixed already.