Fix flaky failure in verify_hashes_mismatch (#9198)

## Summary

I moved this to a separate test. The packages may or may not be
downloaded already, since the previous command fails -- it just depends
on timing.

crates/uv/tests/it/pip_install.rs

@@ -6241,44 +6241,6 @@ fn verify_hashes_mismatch() -> Result<()> {
     "###
     );
 
-    uv_snapshot!(context.pip_install()
-        .arg("-r")
-        .arg("requirements.txt"), @r###"
-    success: false
-    exit_code: 1
-    ----- stdout -----
-
-    ----- stderr -----
-    Resolved 3 packages in [TIME]
-      × Failed to download `anyio==4.0.0`
-      ╰─▶ Hash mismatch for `anyio==4.0.0`
-
-          Expected:
-            sha256:afdb2b588b9fc25ede96d8db56ed50848b0b649dca3dd1df0b11f683bb9e0b5f
-            sha256:a7ed51751b2c2add651e5747c891b47e26d2a21be5d32d9311dfe9692f3e5d7a
-
-          Computed:
-            sha256:cfdb2b588b9fc25ede96d8db56ed50848b0b649dca3dd1df0b11f683bb9e0b5f
-    "###
-    );
-
-    uv_snapshot!(context.pip_install()
-        .arg("-r")
-        .arg("requirements.txt")
-        .arg("--no-verify-hashes"), @r###"
-    success: true
-    exit_code: 0
-    ----- stdout -----
-
-    ----- stderr -----
-    Resolved 3 packages in [TIME]
-    Installed 3 packages in [TIME]
-     + anyio==4.0.0
-     + idna==3.6
-     + sniffio==1.3.1
-    "###
-    );
-
     Ok(())
 }