remove random decimal (#10342)

followup to
- https://github.com/nushell/nushell/pull/9979

## ⚠️ wait for just before 0.86 ⚠️

# Description
after deprecation comes removal 😏 

# User-Facing Changes
`into decimal` is removed in favor of `into float`

# Tests + Formatting

# After Submitting

crates/nu-command/src/default_context.rs

@@ -369,7 +369,6 @@ pub fn add_shell_command_context(mut engine_state: EngineState) -> EngineState {
             Random,
             RandomBool,
             RandomChars,
-            RandomDecimal,
             RandomDice,
             RandomFloat,
             RandomInt,