fix(http provider): correctly propagate Result to caller

Problem: The HTTP config provider has been failing to parse the provided
TOML from its endpoint when polled. My best guess is that including the
`?` on the end of the http provider load results in the TOML parser
subtly exploding due to the aliased return type (`BuildResult`).

It appears that this was broken in
`8ed9ec24c1eba0b2191d7c1f24ec2a7540b5bebf`.

See vectordotdev#21873 for the initial
issue report.

Solution: Correctly propagate the `ConfigBuilder` by not using the `?`
operator. This appears to allow the TOML parser to correctly pick up on
the return type.

-----

Thanks to @jszwedko for the bisect, saved a ton of pain for me.

closes vectordotdev#21873

src/providers/http.rs

@@ -131,7 +131,7 @@ async fn http_request_to_config_builder(
         .await
         .map_err(|e| vec![e.to_owned()])?;
 
-    config::load(config_str.chunk(), crate::config::format::Format::Toml)?
+   config::load(config_str.chunk(), crate::config::format::Format::Toml)
 }
 
 /// Polls the HTTP endpoint after/every `poll_interval_secs`, returning a stream of `ConfigBuilder`.