Rollup merge of #144126 - Shourya742:2025-06-18-fix-target-config-issue, r=Kobzol

Fix empty target_config in apply_rust_config bootstrap

This PR fixes the issue of an empty target_config in apply_rust_config, which was caused by the ordering of TOML config parsing. This was inadvertently introduced during the last config refactor. The test and the corresponding configuration order have been corrected in this PR.

r? ```@Kobzol```

Author: matthiaskrgr