Remove python-like string multiplication (#10293)

# Description
Currently we support "multiplication" of strings, resulting in a terse
way to repeat a particular string.
This can have unintended side effects when dealing with mixed data (e.g.
after parsing data that is not all numbers).
Furthermore as we frequently fall-back to strings while parsing source
code, this introduced a runaway edge case in const evaluation (#10212)

Work for #10233

## Details
- Remove python-like string multiplication.
- Workaround for indentation
  - This should probably be addressed with a purpose built command
- Remove special const-eval error test

# User-Facing Changes
**Major breaking change!**
`"string" * 42` will stop working. (This was used for example in the
stdlib)

We should bless a good alternative before landing this

---------

Co-authored-by: JT <547158+jntrnr@users.noreply.github.com>

crates/nu-parser/src/type_check.rs

@@ -239,8 +239,6 @@ pub fn math_result_type(
                 (Type::Int, Type::Duration) => (Type::Duration, None),
                 (Type::Duration, Type::Float) => (Type::Duration, None),
                 (Type::Float, Type::Duration) => (Type::Duration, None),
-                (Type::Int, Type::String) => (Type::String, None),
-                (Type::String, Type::Int) => (Type::String, None),
 
                 (Type::Custom(a), Type::Custom(b)) if a == b => (Type::Custom(a.to_string()), None),
                 (Type::Custom(a), _) => (Type::Custom(a.to_string()), None),