Change signrawtransaction to signrawtransactionwithwallet in tests, add a test for legacy signrawtransaction

Summary:
This diff updates the signrawtransaction() (to be deprecated) calls with the new signrawtransactionwithwallet() RPC in functional tests.
Because the signrawtransaction is still a valid RPC, also add a test to ensure that there is no regression with it. Not adding this test would left this RPC untested.

From commit eefff65:

scripted-diff:
-BEGIN VERIFY SCRIPT-
sed -i 's/\<signrawtransaction\>/signrawtransactionwithwallet/g'
test/functional/*.py
sed -i 's/\<signrawtransaction\>/signrawtransactionwithwallet/g'
test/functional/test_framework/*.py
-END VERIFY SCRIPT-

From commit d602348:
Add a test for signrawtransaction

Backport 2/3 of core PR10579
(commit eefff65 and part of commit d602348)
This commit arrangement makes it possible to merge the diff:

• without breaking the tests or leaving code untested
• without deprecating signrawtransaction

Depends on D2007
Part of T438

Test Plan:

./test/functional/test_runner.py --extended

Reviewers: #bitcoin_abc, jasonbcox, deadalnix

Reviewed By: #bitcoin_abc, jasonbcox, deadalnix

Subscribers: deadalnix, teamcity

Differential Revision: https://reviews.bitcoinabc.org/D2008