[backport#17304 1/18] MOVEONLY: Reorder LegacyScriptPubKeyMan methods

Summary:
Can verify move-only with:

git log -p -n1 --color-moved

This commit is move-only and doesn't change code or affect behavior.

https://github.com/bitcoin/bitcoin/pull/17304/commits/b4cb18bce3c9a6adab2fa32f3dad4ad966b33be0

Partial backport of Core PR17304

Test Plan:

ninja check

Reviewers: #bitcoin_abc, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Subscribers: jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D7147