Remove generated [profile.release] from new projects

This commit effectively reverts #289 and removes the generated
`[profile.release]` section from `Cargo.toml` when executing `cargo
component new`. The PR mentions that a default release build decreases
from 1.6M to 52KB and that was likely due to stripping DWARF debugging
information rather than many of the other settings configured. Nowadays
for example a default release build (with no extra configuration and no
`profile.release`) is around 50KB because rustc/cargo have started
stripping debuginfo by default in release mode. That means that the
original motivation is still solved, the "default" build is not an
alarmingly large 1.6M.

Otherwise the various settings configured here can have negative effects
which aren't always easy to debug if you're not familiar with them, for
example:

* `lto = true` and `codegen-units = 1` can massively increase the time
  needed for a build. This can be surprising to newcomers who may have
  heard about Rust compile times being bad but this is an order of
  magnitude worse than the default settings. While these two options are
  good rules-of-thumb for a minimally-sized build not everyone falls
  into the category of needing a minimally sized build, and users can
  always configure this themselves.

* `debug = false` is not necessary as it's already the default of the
  `profile.release` in Cargo.

* `strip = true` is no longer necessary in recent versions of
  rustc/Cargo because this is done by default for debuginfo. This is
  otherwise somewhat harmful as it strips the `name` custom section
  which hinders any after-the-fact analysis of a binary because there is
  no symbol information to profile with, for example.

* `opt-level = "s"` is not universally smaller than the default
  `opt-level = "3"` and it can also perform significantly worse. An
  example component I was working with today had a 100% slowdown using
  `opt-level = "s"` relative to `opt-level = "3"`.

Overall I think it's best to inherit Cargo's and Rust's defaults for
these settings by default. There's no one-size-fits-all for all projects
which is why Cargo allows configuring things, but for a template I think
it's best to inherit default settings since that'll ideally cause the
least surprise for users who aren't otherwise familiar with these settings.

src/commands/new.rs

@@ -264,18 +264,6 @@ impl NewCommand {
             doc["lib"]["crate-type"] = value(Value::from_iter(["cdylib"]));
         }
 
-        // add release profile
-        let mut release_profile = table();
-        release_profile["codegen-units"] = value(1);
-        release_profile["opt-level"] = value("s");
-        release_profile["debug"] = value(false);
-        release_profile["strip"] = value(true);
-        release_profile["lto"] = value(true);
-        let mut profile = table();
-        profile.as_table_mut().unwrap().set_implicit(true);
-        profile["release"] = release_profile;
-        doc["profile"] = profile;
-
         let mut component = Table::new();
         component.set_implicit(true);