Fix duplicated words in user-facing messages

[Sreekant13]

What does this PR do?

Spotted a few doubled words in messages that get shown to users while reading
through the code. Nothing functional — just tidying up the wording:

• accelerate config: "used for for how often..." → "used for how often...", and
  "Do you want to to execute..." → "Do you want to execute..." (FP8 prompts)
• launch: "tried to run on on multiple GPUs" → "tried to run on multiple GPUs"
  (error message)
• bnb: "Some modules are are offloaded..." → "Some modules are offloaded..."
  (log warning)

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).

Who can review?

@SunMarc