Parameter injections don't support autocomplete when nested

[shiftinv]

Summary

See title

Reproduction Steps

Create a command, add an injection parameter (arg) which itself has another injection parameter (d). Autocomplete for options of the nested injection parameter doesn't work.

Minimal Reproducible Code

@commands.injection()
def inj1(a: str, b: str):
    return a + b

@inj1.autocomplete("a")  # doesn't work
def autocomp_a(inter, value):
    return [value]

@commands.injection()
def inj2(c: str, d = inj1):
    return c + d

@inj2.autocomplete("c")  # works
def autocomp_c(inter, value):
    return [value]

@bot.slash_command()
async def cmd(inter, arg = inj2):
    await inter.send(arg)

Expected Results

Both a and c have autocomplete enabled.

Actual Results

Only c autocompletes, the a option is registered with "autocomplete": false.

Intents

n/a

System Information

fe2690b5b16b0dcf0aa4676d0213b75250d275dd

Checklist

• [X] I have searched the open issues for duplicates.
• [X] I have shown the entire traceback, if possible.
• [X] I have removed my token from display, if visible.

Additional Context

#670 https://github.com/DisnakeDev/disnake/blob/fe2690b5b16b0dcf0aa4676d0213b75250d275dd/disnake/ext/commands/params.py#L949-L958