MONGOCRYPT-708 pass environment for Alpine task (#873)

MONGOCRYPT-708 use correct artifact for Alpine task

The `--artifact` command was not supplied with an `--env`, resulting in use of the default environment (Ubuntu 22.04).

Removes the redundant `build` command. The `--artifact` command runs the necessary target.

.evergreen/config.yml

@@ -404,10 +404,7 @@ tasks:
   - func: "fetch source"
   - func: "earthly"
     vars:
-      args: +build --env=${earthly_env}
-  - func: "earthly"
-    vars:
-      args: --artifact +build/libmongocrypt-install ${workdir}/install
+      args: --artifact +build/libmongocrypt-install --env=${earthly_env} ${workdir}/install
   - func: "tar and upload libmongocrypt libraries"
 
 - name: build-deb-packages-with-earthly