Private dotenv artifacts not accessible to downstream jobs
### Summary
Linked Issue: https://gitlab.com/gitlab-org/security/gitlab/-/issues/1139
CI/CD pipelines can generate `dotenv` artifacts to pass variables to subsequent jobs in the same pipeline. When the artifact has `public: false` set subsequent jobs in the same project and pipeline no longer load variables from the `dotenv`.
### Steps to reproduce
1. Create a project
2. Set up CI/CD:
<details><summary>CI YAML example</summary>
```yaml
stages:
- artifact
- use_artifact
image: alpine:latest
create-artifact:
stage: artifact
script:
- |
echo VARIABLE=12345 >> data.env
echo OTHER_VARIABLE=this-is-a-key >> data.env
echo VERSION_VARIABLE=1.2.3.4 >> data.env
echo VERSION_TAG=1.2.3.${CI_PIPELINE_ID} >> data.env
echo "SOME_PATHS='/mnt/stars/allsky/ccd_54528347-52c5-49e9-9fe2-65c3a007035f/20240508/day/08_05/ccd1_20240508_055734.jpg,/mnt/stars/allsky/ccd_54528347-52c5-49e9-9fe2-65c3a007035f/20240508/day/08_05/ccd1_20240508_055749.jpg'" >> data.env
artifacts:
public: false
reports:
dotenv: data.env
use-artifact:
stage: use_artifact
script:
- echo -e "Checking variables from last job:\n VARIABLE - $VARIABLE \n OTHER_VARIABLE - $OTHER_VARIABLE \n VERSION_VARIABLE - $VERSION_VARIABLE \n VERSION_TAG - $VERSION_TAG \n SOME_PATHS - $SOME_PATHS"
```
3. Run pipeline and observe that variables are not populated as expected.
</details>
### Example Project
https://gitlab.com/duncan_harris_ultimate_group/dotenv-543743
This example project has a branch with `public: true` where the pipeline works as documented.
### What is the current *bug* behavior?
Jobs in the same pipeline are not able to access non-public `dotenv` artifacts from prior job stages
### What is the expected *correct* behavior?
Downstream jobs in the same pipeline should have access to `dotenv` artifacts
### Relevant logs and/or screenshots
```
$ echo -e "Checking variables from last job:\n VARIABLE - $VARIABLE \n OTHER_VARIABLE - $OTHER_VARIABLE \n VERSION_VARIABLE - $VERSION_VARIABLE \n VERSION_TAG - $VERSION_TAG \n SOME_PATHS - $SOME_PATHS"
Checking variables from last job:
VARIABLE -
OTHER_VARIABLE -
VERSION_VARIABLE -
VERSION_TAG -
SOME_PATHS -
```
### Output of checks
issue