This removes all explicit mention of SCRIPT_DISALLOW_SEGWIT_RECOVERY from validation.cpp

Changes the current behavior by making it impossible to accept segwit recovery transactions
into the mempool, even with -acceptnonstdtxn=1 (this is the same as with all other
script verify flags that are included in standard flags).

Functional test is amended to reflect this change in behavior.

Depends on D3065

make check
./test/functional/test_runner.py
Did IBD with -checkpoints=0 -assumevalid=0