8907df9e02 qa: Ensure wallet unload during walletpassphrase timeout (João Barbosa)
321decffa1 rpc: Fix wallet unload during walletpassphrase timeout (João Barbosa)
Pull request description:
Replaces the raw wallet pointer in the `RPCRunLater` callback with a `std::weak_ptr` to check if the wallet is not expired.
To test:
```
bitcoind -regtest
bitcoin-cli -regtest encryptwallet foobar
bitcoin-cli -regtest walletpassphrase foobar 5 && bitcoin-cli -regtest unloadwallet ""
```
Fixes#14452.
Tree-SHA512: 311e839234f5fb7955ab5412a2cfc1903ee7132ea56a8ab992ede3614586834886bd65192b76531ae0aa3a526b38e70ca2e1cdbabe52995906ff97b49d93c268