`initialfreecoins` does not work for descriptor wallets.

I am not even sure if this should work. If it worked earlier for me. But it does not work now.

Steps to reproduce:
Set the following in the elements.conf file (regtest mode)
```
initialfreecoins=2100000000000000
anyonecanspendaremine=1
```

Create a descriptor wallet
```
elements-cli -named createwallet wallet_name=descriptors_e1 descriptors=true
```
Wait for funds to mature
```
elements-cli -generate 101
```
Check the balance
```
elements-cli getbalance
```
This should be equal to `2100000000000000`, but is `0`. The same works for non-descriptor wallets