fix: stx available balance issues

[alter-eggo]

Try out Leather build ec6d4e3 — Extension build, Test report, Storybook, Chromatic

This pr fixes part of stx balance issues. it sets:

• total balance for balance on home page
• available balance for balance in send form

[markmhendrickson]

Let's add tests here or are you planning to add them more holistically for cases in the underlying issue? (Please link the issue btw)

[alter-eggo]

@markmhendrickson yeah, I'd like to add them separately, also there will be sep pr to support hiro api enhancement