Clean up Segwit Recovery feature

Summary:
Invert meaning of Segwit Recovery flag.
Remove segwit recovery activation
Make SCRIPT_DISALLOW_SEGWIT_RECOVERY a standard flag

Test Plan:
make check
Did IBD on main net and testnet with checkpoints=0 -assumevalid=0.
Update functional test to check for accepting blocks containing segwit recovery transactions,
rejecting segwit recovery transactions from mempool acceptance, and correct network banning.

Reviewers: deadalnix, #bitcoin_abc, markblundeberg, Fabien, jasonbcox

Reviewed By: deadalnix, #bitcoin_abc, markblundeberg

Subscribers: markblundeberg

Maniphest Tasks: T653

Differential Revision: https://reviews.bitcoinabc.org/D3194