Showing string with escaped characters (invalid or special) prints too wide

[Keno]

julia> s = "\xc0\xa0\xe2\x88\xe2|"
Error showing value of type String:

SYSTEM (REPL): showing an error caused an error
ERROR: 1-element ExceptionStack:
Base.InvalidCharError{Char}('\xc0\xa0')
Stacktrace:
  [1] throw_invalid_char(c::Char)
    @ Base ./char.jl:95
  [2] UInt32
    @ ./char.jl:142 [inlined]
  [3] convert
    @ ./char.jl:194 [inlined]
  [4] cconvert
    @ ./essentials.jl:720 [inlined]
  [5] textwidth
    @ ./strings/unicode.jl:276 [inlined]

It's particularly embarrassing, because this is the example we have in the docs to show that we handle this case gracefullly (but we didn't doctest it).

[Keno]

Worked fine on 1.11 - adding to the milestone.

[Keno]

Code was added in #55442.

[vtjnash]

Changed the name, since this issue is now about the (non-regression) of removing the wrong number of bytes from a string like "\$"^1000 or "\xff"^1000 when showing it