e03d6f7ed534f423f58236866f8e83beee1871e1 fuzz: set `m_fallback_fee`/`m_fee_mode` in `wallet_fees` target (brunoerg)
Pull request description:
`m_fallback_fee` and `m_fee_mode` are used in `GetMinimumFeeRate` but we're not setting any value for them in `wallet_fees` target. That's the reason fuzzing is never reaching the following code:

This PR fixes it.
ACKs for top commit:
maflcko:
review ACK e03d6f7ed534f423f58236866f8e83beee1871e1
achow101:
ACK e03d6f7ed534f423f58236866f8e83beee1871e1
murchandamus:
ACK e03d6f7ed534f423f58236866f8e83beee1871e1
Tree-SHA512: 5d364f5351d65762a3ddf88e3abb7bda401b7e4955285e083031d216fb50082b1ea98e2c065aff75a5a8a3d1bc4c2e5e3ca9f9478d902ee8f8d4347b6cbe53af