Use snapshots instead of matching on parts of the output

Personally I liked that the test was only dependent on what really matters, the lack of presence of a particular filename. Now the test would fail if Cargo one day adds more (generated) files to the package.

Co-authored-by: Weihang Lo <weihanglo@users.noreply.github.com>

Author: Byron

tests/testsuite/git.rs

@@ -4249,6 +4249,13 @@ fn simple_with_fifo() {
     // would also be read eventually.
     git_project
         .cargo("package -l")
-        .with_stdout_does_not_contain("blocks-when-read")
+        .with_stdout_data(str![[r#"
+.cargo_vcs_info.json
+Cargo.lock
+Cargo.toml
+Cargo.toml.orig
+src/main.rs
+
+"#]])
         .run();
 }

tests/testsuite/package.rs

@@ -6899,6 +6899,12 @@ fn simple_with_fifo() {
     // Avoid actual blocking even in case of failure, assuming that what it lists here
     // would also be read eventually.
     p.cargo("package -l")
-        .with_stdout_does_not_contain("blocks-when-read")
+        .with_stdout_data(str![[r#"
+Cargo.lock
+Cargo.toml
+Cargo.toml.orig
+src/main.rs
+
+"#]])
         .run();
 }