perf(ext/net): reduce Quinn TLS provider size (#34294)
## Summary
- Switches the Quinn dependency in the networking extension from the
broad `rustls` alias to the explicit AWS-LC Rustls provider feature.
- Avoids enabling Quinn's Ring provider path while keeping the existing
AWS-LC provider authoritative.
- Reduces the measured release-lite binary size on the same execution
target.
## Validation
- `cargo check -p deno_net`
- `cargo build -p deno --profile release-lite`
- QUIC smoke test with `target/release-lite/deno run --allow-all
--unstable-net`
- Same-target release-lite size comparison on `bigboi`: as-built
`315,245,864` bytes to `312,755,832` bytes; stripped scratch copy
`139,131,824` bytes to `136,821,680` bytes.
Co-authored-by: Nathan Whitaker <nathan@deno.com>
