Keymanager FR and GL fixes

[cheatfate]

• Fix behavior set/get of FR/GL for dynamic validators (obtained via Web3Signer) GET /eth/v1/validator/{pubkey}/feerecipient of an existing remotekey returns 404 #6900
• Fix set/get FR/GL could block keymanager from importing keystores Fee Recipient POST resulting in key import blocked #4239

[github-actions]

Unit Test Results

       15 files  ±  0    2 614 suites  +4   1h 13m 20s ⏱️ - 3m 17s
  6 412 tests +  8    5 891 ✔️ +  8  521 💤 ±0  0 ❌ ±0 
44 616 runs  +32  43 898 ✔️ +32  718 💤 ±0  0 ❌ ±0 

Results for commit 6e2b6a1. ± Comparison against base commit 5957497.

♻️ This comment has been updated with latest results.