chore: Simplify tracing with servo_tracing macro (#36661) (#37497)

This pull request refactors existing tracing annotations to leverage the
new `servo_tracing::instrument` macro introduced in #36573.

Specifically, the following transformations were applied:
- Removed `#[cfg_attr(feature = "tracing", ...)]` wrappers.
- Replaced `tracing::instrument` with `servo_tracing::instrument`.
- Removed `level = "trace"`
- Removed `fields(servo_profiling = true)` from tracing attributes
however retained others like `name`. `skip type`

Closes: #36661

---------

Signed-off-by: Bhuwan Pandit <bhuwanpandit109@gmail.com>
Signed-off-by: Jonathan Schwender <55576758+jschwe@users.noreply.github.com>
Co-authored-by: Jonathan Schwender <55576758+jschwe@users.noreply.github.com>

components/layout/Cargo.toml

@@ -62,6 +62,7 @@ unicode-script = { workspace = true }
 url = { workspace = true }
 webrender_api = { workspace = true }
 xi-unicode = { workspace = true }
+servo-tracing = { workspace = true }
 
 [dev-dependencies]
 num-traits = { workspace = true }