chore(ci): remove redundant build profile

It's not clear to me why profile.dev was being written to Cargo.toml by
slim-builds.sh given that all of the values are defaulted.

The one value, `incremental`, that is changed, is changed in
`~/.cargo/config` which will override any profiles.

> The incremental value can be overridden globally with the
CARGO_INCREMENTAL environment variable or the build.incremental config
variable.

https://doc.rust-lang.org/cargo/reference/profiles.html#incremental

I think the release profile is similar, but will be removed by
#6202 so I left it for now.

Signed-off-by: Jesse Szwedko <jesse@szwedko.me>

scripts/slim-builds.sh

@@ -21,19 +21,6 @@ incremental = false
 EOF
 
 cat <<-EOF >> ./Cargo.toml
-[profile.dev]
-# See defaults https://doc.rust-lang.org/cargo/reference/profiles.html#dev
-opt-level = 0
-debug = true
-debug-assertions = true
-overflow-checks = true
-lto = false
-panic = 'unwind'
-# Disabled, see build.incremental
-# incremental = true
-codegen-units = 256
-rpath = false
-
 [profile.release]
 # See defaults https://doc.rust-lang.org/cargo/reference/profiles.html#release
 opt-level = 3