Stop using is_outgoing_transaction

[zancas]

is_outgoing_transaction definition is marked-as-deprecated:

Notes about this deprecated fn:

• this function is a known cause of bugs
• all its call-sites are removed
• except for 1 unit-test all calls were already deprecated.

[zancas]

Superseded by #1215

[zancas]

Keeping open for small bits that might not yet be handled elsewhere.