## Summary
Given a format string like `"{x} {x}".format(x=foo())`, we should avoid
converting to an f-string, since doing so would require repeating the
function call (`f"{foo()} {foo()}"`), which could introduce side
effects.
Closes https://github.com/astral-sh/ruff/issues/10258.
## Summary
This PR resolves an issue raised in
https://github.com/astral-sh/ruff/discussions/7810, whereby we don't fix
an f-string that exceeds the line length _even if_ the resultant code is
_shorter_ than the current code.
As part of this change, I've also refactored and extracted some common
logic we use around "ensuring a fix isn't breaking the line length
rules".
## Test Plan
`cargo test`
