Avoid use of redundant EVG project variables (#1535)

Author: eramongodb

.evergreen/generated_configs/legacy-config.yml

@@ -1002,8 +1002,8 @@ tasks:
   commands:
   - command: s3.get
     params:
-      aws_key: ${toolchain_aws_key}
-      aws_secret: ${toolchain_aws_secret}
+      aws_key: ${aws_key}
+      aws_secret: ${aws_secret}
       remote_file: mongo-c-toolchain/${distro_id}/2023/06/07/mongo-c-toolchain.tar.gz
       bucket: mongo-c-toolchain
       local_file: mongo-c-toolchain.tar.gz

.evergreen/legacy_config_generator/evergreen_config_lib/tasks.py

@@ -407,8 +407,8 @@ def __init__(
                         "params",
                         OD(
                             [
-                                ("aws_key", "${toolchain_aws_key}"),
-                                ("aws_secret", "${toolchain_aws_secret}"),
+                                ("aws_key", "${aws_key}"),
+                                ("aws_secret", "${aws_secret}"),
                                 ("remote_file", "mongo-c-toolchain/${distro_id}/2023/06/07/mongo-c-toolchain.tar.gz"),
                                 ("bucket", "mongo-c-toolchain"),
                                 ("local_file", "mongo-c-toolchain.tar.gz"),