[backport#16822 2/3] gui: fix passphrase labels/tooltip in createwalletdialog/askpassphrasedialog

Summary:
UI improvements:

• update remaining GUI wallet labels and tooltips from passwords to passphrases
• improve grammar of labels in askpassphrase dialog and WalletController::closeWallet

Backport of Core PR16822 - part 2 of 3
Commit https://github.com/bitcoin/bitcoin/pull/16822/commits/539d9403af956c76ae0149a58c07c71a6b58ac69

Depends on D8006

Test Plan:
ninja

Run src/qt/bitcoin-qt, create a new wallet with encryption and check the text in the dialogs.

Reviewers: O1 Bitcoin ABC, #bitcoin_abc, jasonbcox

Reviewed By: O1 Bitcoin ABC, #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D8007