Merge dashpay#6041: fix: adjust signrawtransactionwithkey help text

238978e fix: adjust `signrawtransactionwithkey` help text (UdjinM6)

Pull request description:

  ## Issue being fixed or feature implemented
  `amount` was introduced in dashpay#3101. Double checked the code and yes, we do pass it around (for compatibility reasons) but it doesn’t affect the sig right now, you can set it to 0 or just skip it completely so it should be `optional`, not `required`. We even have a test that uses `signrawtransactionwithkey ` and ignores `amount` https://github.com/dashpay/dash/blob/master/test/functional/rpc_signrawtransaction.py#L19-L46.

  NOTE: It might become required for `sighashtype` with `SIGHASH_DIP0143` flag after dashpay#5860 activation.

  kudos to @pshenmic for noticing

  ## What was done?
  Adjust help text

  ## How Has This Been Tested?
  Run tests

  ## Breaking Changes
  n/a

  ## Checklist:
  - [x] I have performed a self-review of my own code
  - [ ] I have commented my code, particularly in hard-to-understand areas
  - [ ] I have added or updated relevant unit/integration/functional/e2e tests
  - [ ] I have made corresponding changes to the documentation
  - [x] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

Top commit has no ACKs.

Tree-SHA512: e028c46b8b9c1663d9940642b08d56444ab4e5ab33015af1cb99265338b75f9e1c156cbbdd8e00f313bce87117019c769241cc4d83ccd6693ec0ffbaa8940e89

Author: PastaPastaPasta

src/rpc/rawtransaction.cpp

@@ -1031,7 +1031,7 @@ static RPCHelpMan signrawtransactionwithkey()
                             {"vout", RPCArg::Type::NUM, RPCArg::Optional::NO, "The output number"},
                             {"scriptPubKey", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "script key"},
                             {"redeemScript", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "(required for P2SH or P2WSH) redeem script"},
-                            {"amount", RPCArg::Type::AMOUNT, RPCArg::Optional::NO, "The amount spent"},
+                            {"amount", RPCArg::Type::AMOUNT, RPCArg::Optional::OMITTED, "The amount spent"},
                         },
                     },
                 },